Finally, during last summer, one tortoise, which was offered 

 to me for sale, was so helpful, that it gave me eggs directly 

 in my hand, just when I raised it. I appreciated this con- 

 siderable deposit and made the tortoise my house friend". 

 This tortoise deposited many eggs from the ovary and began to 

 develop. However, the development continued only till the 

 10th day, then the embryos died. Concerning the causes of 

 the embryos' death, Baer stated different suppositions 

 (deficiency of humidity, heat, oxygen). In all cases, the 

 early death of embryos is an indication that the course of 

 their development, in many cases, could deviate from norm. 

 Therefore, Baer did not get authentic data about the tortoise 

 development (405) . 



(104) In the figure given in text (p. 407) (Fig. 30), 

 and taken from this work, Baer selected the embryonic thorax 

 (Fig. 17) and its transverse section under 10 times of magni- 

 fication (Fig. 18). According to Baer's opinion, the tortoises 

 are characterized by immersed spinal plates inside the fissure 

 (ab) and by abdominal plates coming forward (be) . This 

 peculiarity of early embryonic development of tortoises is 

 referred to by Baer to explain the peculiarity of the forma- 

 tion of axial skeleton and ribs in the formulated animals. 

 This conclusion is undoubtedly erroneous, because the region 



ab in Fig. 18 is the spinal canal, and the region be — is what 

 is called spinal plates by Baer. The confirmation of Baer 

 that the extremities in the tortoises are formed in a way 

 different from other animals, is also incorrect. The deficiency 

 of materials and disturbances of development, connected with 

 the unsuitable conditions of egg maintenance, were the sources 

 of the erroneous conclusions (405) . 



(105) Baer's investigations on the embryology of man 

 were known in Russia. Brief popular statements of the 

 phenomenon of conception and embryonic development of man were 

 given by P. F. Goryaninov in the artle "Development of human 

 embryo in the uterus", which was published in 1887 ("Drug 

 zdraviya" (public medical journal), No. 32, pp. 241-243, 4°). 

 In this article, Goryaninov talked only about two layers — 

 external and internal. "From internal, he wrote, the intestinal 

 canal, lungs, mesentery and other vegetative organs are formed, 

 and from the external ^animal region skeleton, muscles and skin. 

 Obviously, Goryaninov, not wishing to go into details, dis- 

 tinguished only the regions of the embryo, which were called by 



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