Langley, John Newport

(b. Newbury, England, 2 November 1852; d. Cambridge, England, 5 November 1925)

Physiology, histology.

Professor physiology at Cambridge from 1903 until his death, Langley was renowned for his studies of glandular secretion and of the autonomic, or involuntary, nervous system. He was the second son of John Langley, a private schoolmaster at Newbury, who prepared him at home for Exeter Grammar School, where his uncle, Rev. H. Newport, was headmaster. His mother, Mary, was the eldest daughter of Richard Groom, assistant secretary to the Tax Office, Somerset House. In autumn 1871 Langley matriculated with a sizarship at St. John’s College, Cambridge, where e later won a scholarship. During his first five terms he read mathematics and history as preparation for a place in the civil service, at home or in India. In May 1873 Langley enrolled in a newly created course in elementary biology offered by Michael Foster, who had come to Cambridge in 1870 as Trinity College praelector n physiology. Under Foster’s inspiration Langley abandoned his former plans and began to read for the natural sciences tripos, in which he took first-class honors in 1874.

Langley graduated B.A. in 1875 and in 1876 succeeded Henry Newell Martin as Foster’s chief demonstrator, his salary being paid by Trinity College, where he was elecvted to a fellowship in 1877. Also in 1877 Langely spent several months in the laboratory of Wilhelm Kuumlhne in Heidelebrg, where he studied salivary secreation in the cat. Langley received an M.A. from Cambridge in 1878 and an Sc.D. in 1896. From 1883 to 1903 he was university lecturer in physiology and lecturer in natural science at Trinity College. In 1900 he was named deputy professor to foster and in 1903 succeeded him as professor hysiology. In 1914 a large new physiological laboratory was built at Cambridge under Langley’s direction with funds provided by the Drapers’ Company. Upon Langley’s death in 1925 the chair passed to Joseph Barcraft.

Elected to fellowship in the Royal Society in 1883 and awarded its Royal Medal in 1892, Langley also served as a member of its Council (1897-1898) and as vice-president (1904-1905). He was president of the Neurological Soceity of Great Britain in 1893 and president of the physiological section of the british Association in 1899. He was awarded the Baly Medal of the Royal College of the Swedish Society of Physicians in 1912, and honorary doctorates by the universities of Dublin, St. Andrews, Groningen, and Strasbourg. In 1902 he married Vera Kathleen Forsyth-Grant of Ecclesgreig, Kincardineshire, by whom he had one daughter.

Langley’s career in research fell into two major phases. From 1875 to 1890 he devoted himself largely to glandular secreation, and from 1890 until his death he worked mainly upon the involuntary nervous system. At the very beginning of his career, however, Langley briefly joined the group of Cambridge researches who were working in the area of Foster’s special interest, the problem of the heartbeat. During the winter of 1874-1875 Foster gave Langley a small amount of the alcoholic extract of jaborandi and asked him to study its physiological action. By October 1875 Langley’s focus had narrowed to the effects of the drug on the heart. His major concluson—that jaborandi altered heart action not by acting on any nervous elements but, rather, bu acting directly on the cardiac tissue itself—conformed nicely to Foster’ own myogenic view of heart action.¹

But Langley was quickly distracted form the problem of the heartbeat. One of the most striking effects of jaborandi was to evoke copious secretion from the submaxillary gland. Recognizing in this phenomenon an opportunity to clarify the nature of salivary secretion and of secretion in general, Langley salivary secretion and of secretion in general, Langley undertook a systematic study of the secretory organs which occupied him for the next fifteen years. In a series of papes remarkable for technical ingenuity and theoretical caution, Langley challenged Rudolf Heindenhain’s generally accepted views on the structural changes which take place in secreting glands and on the relationship between glandular secretion and nervous activity.

As early as 1879 Langley had begun to develop the view that gland cells become more granular during rest and less granular during secretion, a conclusion precisely the reverse of Heidenhain’s.² In making this point Langley emphasized that the structural changes observed in secreting glands are progressive and gradual, with no dramatic turning points discernible in the underlying processes. By 1888 Langley was also prepared to dispute Heidenhain’s theory that the salivary glands are supplied not only with secretory nerves but also with “trophic” (metabolic) nerves whose function is to increase the solubility of stored gland substance.³ With increasing confidence Langley argued that the evidence adduced in support of “trophic” nerves was either unreliable or could more plausibly be ascribed to the effects of local vasomotror nervous action. To the end of his career Langley maintained that the salivary gland, at least, is supplied with but one king of nerve, which can by itself produce all of the changes observed in glandular secretion.⁴

In the 1880’s, although engaged chiefly in these studies on seretion, Langley also undertook studies of the normal anatomy of the dog’s brain and of nervous degeneraton in the decorticated dog. Although this work from its beginning was related to the celebrated controversy between David Ferrier and Friedrich Goltz over cerebral localizaton, Langley seems never to have taken a definitive position on the issue.⁵ Also in the 1880’s Langley devoted himself briefly to the fashionable and controversial subject of hypnotism. Reputedly an accomplished hypnotist himself, chiefly because of his remarkable steely blue eyes, Langley sought to subsume many of the hypnotic phenomena under the physiological concept of irradiated inhibition.⁶

Although Langley’s work on glandulr secretion had involved him from the outset with problems of sympathetic innervation, his subsequent concentration on the involuntary nervous system was not a direct outgrowth of his work on the secretory nerves. Rather, it had its origin in the discovery that nicotine could selectively interrupt nerve impulses at the sympathetic ganglia. In a joint paper announcing the discovery in 1889, Langley and William Lee Dickinson emphasized its immense potential as an analytic tool. In particular it seemed to offer an unimpeachable means of distinguishing those nerve fibers which merely ran through the ganglion without being connected with its nerved cells.⁷ Although one alumnus of the Cambridge school has claimed in private correspondence that the discovery was really Dickinson’s alone and not Langley’s,⁸ it was certainly Langley who most brilliantly and successfully exploited the new technique. Scarcely six months after the discovery, he had applied studies on the innervation of the salivary gland.⁹ Thereafter the range of his studies expanded dramatically. Bu using nicotine in concert with more traditional techniques, such as nerve degeneration, Langley wa able to map out the plan of much of the invouluntary system in exquisite and unpreceedented detal. In so doing he built upon the important earlier work of his Cambridge colleague W. H. Gaskell, and their combined contributions made Cambridge of sometime the leading center for research on the involuntary nervous system.

Chiefly on histological grounds, Gaskell had established that the “visceral”, or involuntary, nerves arise from the central nervous system in three distinct outflows: the cervicocranial, the thoracic, and the sacral. Gaskell’s study of the distribution of the gray and white rami had also convinced him that the involuntary system is not essentially independent of the cerebrospinal system, as had been thought. While Langley’s work strongly reinforced these fundamental generalizations, it also extended and modified Gaskell’s results in several important ways. In the 1890’s, at first with Charless Sherrington but mainly alone, Langley charted the distribution of the efferent sympathetic fibers to the skin and their relation to the afferent fibers if the corresponding spinal nerves. In so doing he not only clarified the basis for various pilomotor mechanisms (bristling of hair in cats and dogs, ruffling of feathers in birds) but also contributed importantly to clinical attempts to understand “referred” cutaneous pain in certain visveral diseases.

Moreover, these studies of the pilomotor nerves provided much of the evidence for three of Langley’s most original contributions to the histology and physiology of the involuntary nervous system: (1) the conclusion that peripheral ganglia are not collected together according to function, as some had thought, but instead are associated with definite somatic areas, each ganglion being supplied with all of the sympathetic fibers of whatever function (whether inhibitory, motor, or other) which run to its associated area; (2) the discovery that every efferent nerve fiber passes through only one nerve cell on its way to the periphery, a discovery which overturned the hitherto rather casual assumption that such a fiber might run through several nerve cells (or even none), and which therefore had important physiological implicatiosn; and (3) his concept of “axon reflexes,” developed in opposition to those French workers who followed Claude Bernard in their belief that peripheral ganglia are capable of true reflex action. The issues involved in this dispute are extremely complex, but Langley’s basic conclusions were that the supposed ganglionic reflexes take place in the absence of afferent arcs and that they have their origin not in peripheral ganglia but in efferent preganglionic axon processes.

Another of langley’s influential contributions dating from the late 1890’s was his successful introduction of a radically new nomenclature for what had been earlier (and loosely) designated the “organic,” “vegetatiave,” “sympathetic,” “visceral,” or “involuntary” nervous system. On the suggestion of Richard Jebb, professor of Greek at Cambridge, Langley proposed instead the term “autonomic,”¹⁰ which still retains its preferred status. Langley there after confined the term “sympathetic” to the thoracic outflow of the autonomic system and introduced the term “parasympathetic” to designate its cranial and sacral outflows. By attaching this single name to both the cranial and sacral outflows, Langley wished to emphasize that these nerves belong to a somewhat separate system (which he sometimes called the “oro-anal” system), in that they resemble each other in their action and phylogenetic origin more than they resemble the thoracic (or “sympathetic”) nerves. Langley gathered much of the evidence for the existence of this separate, parasympathetic system, although he perhaps tended to minimize the extent to which the idea was already present in Gaskell’s earlier work. The importance of “merely” nomenclatural contributions tends to be greatly underrated, but Langley’ terminological precision undeniably promoted clarity of thought and conciseness of expression in subsequent literature on the autonomic system. Still other contributions by Langley from the 1890’s, perhaps less striking than those already described but characteristically thorough and valuable, were the studies he undertook with H. K. Anderson on the neuromuscular mechanisms of the iris and on the pattern of innervation for the pelvic organs.

Between about 1900 and 1905 Langley’s most important new work centered on experimental cross unions of different kinds of nerve fibers. While confirming the functional distinction between efferent and afferent nerve fibers, these cross unions demonstrated the essential functional similarity of all efferent, preganglionic fibers and pointed to the conclusion that the final action of a peripheral nerve fiber depends not on the nature of the fiber itself, nor on the nature of the impulse which it transmits, but on the nature of the tissue in which it ends.

By 1905 Langley had entered perhaps the most fertile phase of his remarkable prouctive career. The subject to which he now turned was the mode by which nerve impulses or other stimuli are transmitted to various effector cells—whether muscular, glandular, or ganglionic. Here again nicotine and other drugs (especially curare and adrenaline) were utilized as fundamental analytic tools. The background for this new phase of Langley’ work was formed in part by his earlier observation that nicotine could stimulate peripheral ganglia even after their preganglionic fibers had degenerated, but, more immediately, by the discovery of adrenalin in 1895 and the revelation soon afterward of its sympathomimetic effects on both normal and denervated muscle or gland cells. That nicotine and adrenalin produced the same effects on denervated as on normal cells raised doubts about the prevailing view that these and other drugs ordinarily act on nerve endings. These doubts were strikingly confirmed by Langley’s discovery in 1905 that curare abolishes the slight tonic contractions produced in certain skeletal muscles of the fowl by injection of nicotine. Since this result occurs even after degeneration of the nerve fibers to these muscles, Langley argued that it can only be referred to the mutually antagonistic action of nicotine and curare on striated muscle. And this mutual antagonism could best be understood as the result of a competition between nicotine and curare for some constituent of the muscle substane with which each formed a specific chemical compound.

On grounds such as these Langley was able to suggest in 1906 that every cell connected with an efferent fiber contains a substance responsible for the chief function of that cell (whether contraction, or secretion, or—in the case of nerve cells—the discharging of nerve imuplses) as well as other “receptive substances” capable of reacting specifically with chemical bodies (drugs) or sometimes with nervous stimuli. Although the tangled web of issues and influences has yet to be unraveled by historians, it seems clear that Langley’s concept of “receptive substances” formed part of the background for later theories of the humoral transmission of nervous impulses¹¹ and that it provided a stimulus to many subsequent studies in neuromuscular physiology. Langley himself elaborated his theory in several later studies.

With the advent of World War I, Langley and his depleted staff directed their energies and the facilities of their new laboratory toward studies of more immediate clinical relevance. Special attention was given to means of repairing denervated and atrophied muscle tissue, although Langley’s typically cautious and thorough investigation offered little hope to those treating or suffering from such affliction. His experiments on animals seemed to show that neither electical stimulation nor massage nor any other physiotherapeutic measures could prevent atrophy in denervated muscle tissue. From the end of the war until his death, Langley worked chiefly on various aspects of vasomotor action, most notably the so-called “antridromic” vasodilatation produced in the hind limb by stimulating certain posterior nerve roots at their entry into the spinal cord. This phenomenon attracted considerable attention because it seemed to offer a unique exception to the Bell-Magendie law of the functional distinction between efferent and afferent fibers. In Langley’s view, however, antidromic vasodilatation was produced by metabolites set free in muscle spindle cells by impulses passing down afferent fibers, and was therefore not an exception to the law.

In 1921 Langley gathered the results of much of his research in The Autonomic Nervous System, part I. (A projected second part never appeared.) Soon translated into French and German, this work was conceived in part as a rival to Gaskell’s posthumous The Involuntary Nervous System (1916). Sensitive to suggestions that he had merely followed a path laid out for him by Gaskell, Langley in 1919 wrote a long letter to Lancet emphasizing the extent and manner in which his work had gone beyond Gaskell’s and pointing to the latter’s book as one possible factor impending proper recognition of his own work. In this letter Langley also emphasized that all of his work on the autonomic system had evolved logically from the studies he had undertaken with Dickinson in 1889 on nicotine and related poisons.¹²

One final contribution of Langley’s deserves mention. In 1894 he assumed editorial and financial control of the Journal of Physiology, which had acquired both a high reputation and a sizable debt since its founding by Foster in 178. Besides arranging to pay off the debt and accepting the unsold stock, Langley substituted a policy of fiscal, verbal, and theoretical economy for Foster’s rather genial and indulgent editorial policy. From 1894 until his death Langley invested enormous energy and talent in his editorial tasks, although he generously allowed Foster to retain the official title of editor until the latter’s death in 1907.

Under Langley’s direction the Cambridge School of Physiology preserved and enhanced the great reputation it had gained under Goster’s initial inspiration. Before assuming the professorship Langley had taught only advanced students, but he thereafter followed Foster’s example by taking responsibility for the introductory lectures. In the latter capacity he was not notably successful, being both too reserved and too exacting to carry most novices with him. In fact, even a few of his advanced students and colleagues apparently resented his reserve and his alleged egotism; and there is some evidence that personal relationships were consequently strained in the Cambridge physiological laboratory.¹³ Like many members of the Cambridge school, Langley was an accomplished athlete; his performences in sprinting, rowing, tennis, and golf were overshadowed by his prodigious talent as a skater. For one of his less avid admirers, this talent was perfectly in keeping with the spirit of Langley’s work and character—“brilliant technique on an icy background.”¹⁴

NOTES

1. See J. N. Langley, “The Action of Jaborandi on the Heart,” in Journal of Anatomy and Physilogy,10 (1876), 187-201; and G. Geison, Michael Foster, pp. 377-82.

2. J. N. Langley, “On the Structure of the Serous Glands in Rest and Activity,” in Proceedings of the Royal Society,29 (1879), 377-382.

3.See J.N. Langley, “On the Physiology of the Salivary Secretion. Part IV, The Effect of Atropin Upon the Supposed Varieties of Secretory Nerve Fibres,” in Journal of Physiology,9 (1888), 55-64, esp. 61-62; and J. N. Langley to E. A. Schaumlfer, 4 Feb, 1888, Sharpey-Schafer Papers, Welcome Institute of the History of Medicine.

4. See, for example, J. N. Langley, “Note on Trophic Secretory Fibres to the Salivary Glands,” in Journal of Physiology,50 (1916), XXC-XXVI,

5. See E. Klein, J. N. Langley, and E. A. Schäfer, “On the Cortical Areas Removed From the Brain of a Dog, and From the Brain of a Monkey,” ibid.,4 (1883), 231-247; J. N. Langley, “the Structure of the Dog’s Brain,” ibid., 248-285; and “Report on the Parts Destroyed on the Right Side of the Brain of the Dog Operated on by Prof. Goltz,” ibid., 286-309; J. N. Langley and C. S. Sherrington, “Secondary Degeneration of Nerve Tracts Following Removal of the Cortex of the Cerebrum in the Dog,” ibid.,5 (1884), 49-65; and J. N. Langley and A. S Gruumlnbaum, “On the Degenreation Resulting From Removal of the Cerebral Cortex and Corpora Striata in the Dog,” ibid.,11 (1890), 606-628. In private correspondence Langley did once refer to an apparently fleeting hypothesis of his on the issue of cerebral localization, but the content of this “hypothesis” remains obscure. See J. N. Langley to e.A. Schaumlfer, 23 Feb. 1884, sharpey-Schafer Papers, Wellcome Institute of the History of Medicine.

6. See J. N. Langley, “The Physiological Aspect of Mesmerism.” in Proceedings of tyhe Royal institution of Great Britain,11 (1884), 25-43; and J. N. Langley and H. E. Wingfield, “A Preliminary Account of Some Observations on Hypnotism,” in Journal of Physiology,8 (1887), XCII-XXIV.

7. J. N. Langley and W. Lee Dickinson, “On the Local Paralysis of Peripheral Ganglia, and on the Connexion of Different Class of Nerve fibres with Then,” in Proceedings of the Royal Society,46 (1889), 423-431.

8. W. Langdon-Brown to Donal Sheehan, 11 Mar. 1940, copy deposited in the obituary files, Medical Historical Library, Yale University.

9. J.N. Langley, “On the Physilogy of the salivary Secretion. Part VI. Chiefly Upon the Connection of Peripheral Nerve Cells With the Nerve Fibres Which Run to the Sublingual and Submaxillary Glands,” in Journal of Physiology,11 (1890), 123-158.

10. See J. N. Langley, “The Sympathetic and Other related Systems of Nerves,” in Text-Book of Physilogy, E.a. Schaumlfer, ed., 2 volts. (Edinburgh-london, 1898-1900), II, 616-696, esp. 659-660.

11. See, e.g., Walter B. Cannon, “The Story of the Development of Our Ideas of Chemical Meditation of Nerve Impulses,” in American Journal of the Medical Sciences, n.s. 188 (1934), 145-159. According to Henry dale, however, langley reacted unfavorably toward, and diverted attention from, the hypothesis of the chemical transmission of nerve impulses as originally proposed by T. R. Elliot in 1904. See H. H. Dale, “T.R. Elliott,” in Biographical Memoirs of Fellows of the Royal Society,7 (1961), 53-74, esp. 63-64.

12. J. N. Langley, “The Arrangement of the Autonomic Nervous System,” in Lancel (31 May 1919), p. 951.

13. Most notably in the letter of Walter Langdon-brown to Donal Sheehan (see note8). See also J. F. Fulton to Donal Sheehan, 27 Mar. 1940, copy deposited in obituary files, Medical Historical Library, Yale University. For a rather more favorable view of Lanbgley’s personality, see the obituary notices by W. M. Fletchre.

14. Langdon-Bronw to Sheehan (note 8).

BIBLIOGRAPHY

I. Original Works. Of Langley’s approximately 170 published research papers, the great majority appeared in the Journal of Physiology. a virtually complete bibliography, slightly flawed by occasional errors or omissions in pagination, is given by Walter Morley Fletcher in Journal of Physiology,61 (1926), 16-27. Fletcher did overlook the important letter to Lancet cited in note 12 and the obituary notice on Lucas (cited below). The Royal Society Catalogue of Scientific Papers, X, 510-511; XVI, 595-596; lists Langley’s papers up to 1900.

Langley’s major contributions to the physiology of glandular secretion are contained in the six-part article “On the Physiology of the Salivary Secretion,” in Journal of Physiology,1 (1878), 96-103, 339-369; 6 (1885), 71-92; 9 (1888), 55-64; 10 (1889), 291-328; and 11 (1890), 123-158. the full measure of those contributions is made clear in Langley’s admireable review articel “The Salivary Glands,” in Text-Book of Physiology, E.A. Schaumlfer, ed., 2 vols. (Edinburgh-London, 1898-1900), I, 475-530.

So extensive and rich was Langley’s work on the autonomic nervous system that only a few of his major papers can be listed here. On his studies of the pilomotor nerves, see especially “On Pilomotor Nerves,” in Journal of Physiology,12 (1891), 278-291, written with C. S. Sherrington; and “The Arrangement of the Sympathetic Ner vous System, Based Chiefly on Observation Upon Pilo Motor Nerves,” ibid.,15 (1893), 176-244. langley’s work wih H. K. Anderson on the innervation of the pelvic and adjoining viscera is described in a seven-part article, ibid.,18 (1895), 67-105; 19 (1895), 71-84, 85-121, 122-130, 131-139; 19 (1896), 372-384; and 20 (1896), 372-406. On the concept of “axon reflexes,” see “On Axon-reflexes in the Pre-ganglionic Fibres of the Sympathetic System,” ibid.,25 (1900), 364-398.

Langley’s concept of “receptive substances” was first announced in “On the Reaction of Cells and of Nerve-Endings to Certains Poisons, Chiefly as Regards the Rection of Striated Muscle to Nicotine and Curare,” ibid.,33 (1905), 374-413. More impressive for its scope and clarity is his Croonian lecture lecture for 1906, “On Nerve-Endings and on Special Excitable Substances in Cells,” in Proceedings of the Royal Society,76B (1906), 170-194. The concept was further developed in a four-part articel, “On the Contraction of Muscle, Chiefly in Relation to the Presence of ‘Receptive Substances,’” in Journal of Physiology,36 (1907), 347-384; 37 (1908), 165-212, 285-300; and 39 (1909), 235-295.

For Langley’s more general accounts of the autonomic nervous system, see his superb article “The Sympathetic and Other Related Systems of Nerves,”i; in Text-Book of Physilogy, II. 616-696; his presidential address to the physiological section of the British Association, in Report of the Sixty-Ninth Meeting of the British Association for the Advancement of Science (London, 190), pp. 881-892; “The Autonomic Nervous System,” in Brain,26 (1903), 1-26; and, of course, his monograph The Autonomic Nervous System, pt. 1 (Cambridge, 1921). For a clear and succinct account of the rationale for Langley’s nomenclatural innovations, see “The Nomenclature of the Sympathetic and of the Related System of Nerves,” in Zentralblatt für Physiologie,27 (1913), 149-152.

For examples of Langley’s wartime research on denervated muscle, see “The Rate of Loss of Weight in Skeletal Muscle After Nerve Section With Some Observations on the Effect of Stimulation and Other Treatment.” in Journal of Physiology,49 (1815), 432-440, written with Toyojiro Kato; and “Observations on Denervated Muscle,” ibid.,50 (1916), 335-344. Langley’ major postwar research projects are described in three two-part articles: “The Secreton of Sweat,” ibid., 56 (1922), 110-119, 206-226; and “Antidromic Action,” ibid.,57 (1923), 428-446, 58 (1923), 49-69.

Langley also wrote useful obituary articles on four of his Cambridge colleagues—Michael Foster, in Journal of Physiology,35 (1907), 233-246; w. H. Gaskell, in Proceedings of the Royal Society88B (1915), xxvii—xxxvi; Arthur Sheridan Lea, ibid.,89 (1916), xxv-xxvii; and Keith Lucas, in Nature, 98 (1916), 109. The obituary on Gaskell is noteworthy for its generous assessment of the work of his sometime rival. The range of Langley’ interests is indicated in a historiographically undistinguished article, “Sketch of the Progress of Discovery in the Eighteenth Century as Regards the Autonomic Nervous System,” in Journal of Physiology,50 (1916), 225-258. Besides his monograph on the autonomic nervous system, Langley’s published books were Practical Histology (London, 1901; 3rd ed., 1920); and, initially with Michael Foster, A Course of Elementary Practical Physiology (London, 1876; 7th ed., 1899); by the 7th ed., L. E. Shore was listed as coauthor.

There is apparently no central repository for Langley’s letters or papers, and little seems to have survived. Some ten letters from him to E. A. Schäfer are to be found in the Sharpey-Schäfer Papers at the Wellcome Institute of the History of Medicine, London.

II. Secondary Literature. For valuable obituary notices, see W. M. Fletcher, in Journal of Physiology,61 (1926), 1-27, which contains a full bibliography; and in Proceedings of the Royal Society,101B (1927), xxxiii—xli; and C. S. Sherrington, in Dictionary of National Biography, 1922-1930, pp. 478-481. For background on some of Lanley’s research and on his place in the Cambridge school, see Gerald L. Geison, “Michael Foster and the Rise of the Cambridge School of Physiology” (unpublished Ph. D. dissertation, Yale, 1970). His place in the recent history of pharmacological physiology and junctional transmission receives brief attention in Alfred Fessard, “Claude Bernard and the Physiology of Junctional Transmission”, in Claude Bernard and Experimental Medicine, Francisco Grande and Maurice B. Visscher, eds. (Cambridge, Mass., 1967), pp. 105-123, esp. p. 116; and F. E. Shideman, “Drugs as Tools in the Elucidation of Physiological Mechanisms,” ibid., pp. 125-134, esp. pp. 125-127.

Gerald L. Geison