ROSA, DANIELE

(b. Susa, near Turin, Italy, 29 October 1857; d. Novi Ligure, Italy, 30 April 1944)

zoology.

Rosa studied science and medicine at Turin, receiving the doctorate in 1880. He completed his training under Ernst Ehlers at the zoology institute of the University of Göttingen, then was an assistant at the zoology museum in Turin. Later he taught zoology and comparative anatomy at the universities of Sassari, Modena, Florence, Turin, and, again, Modena. He retired in 1932.

Rosa published works on the morphology and systematics of the oligochaetes (Annelida). In two monographs that appeared in 1899 and 1918 he set forth his own theory of the origin of species and of their transformations. He held that the extinction of species results primarily from a steady decrease in variability and postulated a “law of progressively diminished variation”: the longer a species has been in existence, the less it varies. Since the lower species supposedly possessed a better-preserved capacity for variation, in the course of time they replaced the higher species. The law was concerned essentially with causes, which were unknown. Rosa therefore changed its basis to what lie termed a “law of progressively diminished variability.” The effect of this law was slowed, however, because not all parts of an animal become modified—and therefore reach an end point—simultaneously. Nevertheless, a consequence of the law was that the emergence of new forms eventually ceased. Rosa’s law also asserted the existence of orthogenesis in nature. This orthogenesis, he claimed, was not affected by individual variations, since the latter, which were “Darwinian” as opposed to “phylogenetic,” had, in his view, no influence on the transformation of species. The theory found no supporters.

BIBLIOGRAPHY

Rosa’s main works are La riduzione progressiva della variabilità ed i suoi rapporti coll’estinzione e l’origine della specie (Turin, 1899), translated into German as Die progressive Reduktion der Variabilitāt und ihre Beziehungen zum Aussterben und zur Entstehung der Arten (Jena, 1903); and Ologenesi. Nuova teoria dell’evoiuzione e della distribuzione geografica dei viventi (Florence, 1918), translated into French as L’ologenèse. Nouvelle théorie do l’évolution et de la distribution géographique des êtres vivants (Paris, 1931). An obituary on Rosa is Celso Guareschi, in Dall’ Annuario dell’Università di Modena Anni acc. (1942–1944), 269–270.

Hans Querner