The idea of spontaneous development, actually in somewhat 

 variable form, found support at a later time between 1840 

 and 1850, for example in the work of the amateur naturalist 

 Gros,55 w ho W as interested mainly in the origin and development 

 of parasitic worms. He published his articles in the BULLETIN 

 OF THE MOSCOW SOCIETY OF NATURE INVESTIGATORS in the 

 period from 1845 to 1855. 



Gros' earliest work^6 began with various microscopic 

 investigations; besides observations on ticks, ascarids, 

 tapeworms taken from snipe intestines, blood filaria, vaginal 

 and intestinal trichomonads, and vibrions from the mouth cavity 

 and human feces, there is a section on the development of the 

 worm, in which Gros assumed that rotifers could develop from 

 particular eggs. In the same report Gros described the embryonic 

 development of the filaria, and gives explanations of the early 

 stages of division. 



A paper he published in 1849, 5? like the previous one, 

 began with a variety of parasitological and embryological 

 observations. He described a worm with five openings, a nematode 

 from a tortoise intestine, an amoeba from a human mouth cavity, 

 observations on blood parasites and infusoria, and, finally, 

 some embryological data. Gros described his observations on 

 the development of the eggs of human ascarids and pinworms, 

 and he described briefly the structure and development of 

 fresh-water moss and his observations on embryonic chick 

 development. In this section he reported work on the structure 

 of the yellow granules, on the differentiation of embryonic 



55. Biographical information about George Gros was not 

 available. In the card index of the members of the Moscow 

 Society of Nature Investigators, in which he was named 

 Egor Egorvich Gro, it was recorded that Gros was considered 

 an active member of the Society from March 16, 1844, and 

 frequently participated at the meetings with introductory 

 presentations, and that his articles were printed in the 

 BULLETIN of the Society. 



56. Gros, "Observation et inductions microscopiques , " BULL. 

 SOC. NAT. MOSCOW, 18 (1845), pp. 380 - 428. 



57. Gros, "Fragment d'helminthologie et de physiologie 

 microscopique," BULL. SOC. NAT. MOSCOW, 22 (1849), 

 pp. 549 - 573. 



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