ovary and received in the oviducts. (86) Other observers 

 considered this incorrect but could not find an accurate 

 solution. Also, in 1797 (William) Cruikshank (87)7 reported 

 that he saw the ovum in the oviduct of a rabbit within three 

 days after mating. There, the ova were much smaller than 

 the Graafian vesicles. At first, he was not believed, and 

 Prevost and Dumas** (88) in 1824 failed to confirm his 

 observations on dogs and rabbits. Baer highly regarded the 

 work of the French embryologists," but he contended that 

 they were not concerned with the ova but with the early 

 embryos. 



Already in 1826, Baer had seen many times small trans- 

 parent ova (1 - 3 mm in diameter) in the horns of the uterus 

 and in the oviducts; in spring 1829, he observed significantly 

 smaller and less transparent ova. He did not doubt that these 

 bodies actually were ova, because he assumed that the yolk of 

 the mammalian egg is non- transparent as it is in birds. Thus, 

 Baer described how he accomplished this last step: 



William Cruikshank, "Experiments in which, on the third 

 day after impregnation, the ova of rabbits were found 

 in the fallopian tubes, and on the fourth day after 

 impregnation in the uterus itself? with the first 

 appearance of the foetus," PHILOSOPHICAL TRANSACTIONS 

 of the Royal Society of London, 87 (1797), pp. 129 - 137. 

 J. L. Prevost et J. A. Dumas, " Nouvelle theorie de la 

 generation . " Deuxieme memoire , "Rapports de 1 ' oeuf avec 

 la liqueur fecondante. Phenomenes appreciables , resultant 

 de leur action mutuelle. Developpement de l'oeuf des 

 batraciens," ANN. SCI. NAT., 2 (1824), pp. 100 - 121, 

 129 - 149. Troisieme memoire, "De la generation dans les 

 mammiferes et des premiers indices du developpement de 

 l'embryon," ibid . , 3, pp. 113 - 138. 



However, in the introduction to the second volume of 

 UBER ENTWICKLUNGSGESCHICHTE, Baer talked about the 

 mistakes of Prevost and Dumas in a fairly ironical 

 tone. 



288 



