possibility of artificial fertilization in different marine 

 animals (116) . 



Baer noted that since the time of Spallanzani it was 

 known that it is easy to fertilize artificially the ova of 

 frogs. Spallanzani (and later Rossi) inseminated a bitch 

 by the artificial introduction of sperm. Baer's contempo- 

 raries, according to him, questioned these data, although 

 without foundation, because Bischoff's work had made it 

 apparent that in mammals and also in other animals, the 

 separation of the ovum is due to its maturation and not a 

 result of copulation. 



Baer thought it evident that every mature ovum intro- 

 duced into contact with sperm of the same species is 

 fertilized and, if situated in suitable conditions, develops 

 into an embryo. Sometimes experimental difficulties arise, 

 which can, however, be overcome. His failures in Petersburg 

 with artificial insemination of fish ova Baer explained by 

 unsuitable temperature conditions. 



In Genoa at the end of August 1845 Baer made the first 

 experiments in the artificial insemination of the ova of 

 Ascidians. "In the earliest hours," Baer wrote, "the division 

 began, and before the day had passed larvae hatched in the 

 form of large cercariae." The experiment of artificial 

 insemination of mature ova of the sea urchin, carried out 

 on the same day, was also crowned with success. Within 

 sixteen hours freely moving embryos developed. "It was a 

 very great success for one day," Baer stated: "a researcher 

 rarely succeeds sufficiently to exclaim VENI, VIDI, VICI! 

 After the first glitter, I was on top of the world" (p. 233). 

 However, it was extremely difficult to keep the ascidian 

 larvae alive. They died within hours after hatching; the 

 sea urchin larvae did not live more than four days. 



Gaining success in the artificial fertilization of the 

 ova of sea urchins, Baer turned to study their development. 

 He observed the early stages of development at first in Genoa 



13. Extracts from this report were published in FRORIEP 



NOTITZEN (1846, No. 39, pp. 38-40) under the heading, 

 K. E. v. Baer, "Neue Untersuchungen iiber die Entwickelung 

 der Thiere . " 



467 



