the first sound basis for the history of development 

 of animals were members of Your Academy. First was 

 Caspar Friedrich Wolff, the father of eternal glory, 

 of whom in all the world I have seen very few so 

 clever, nor have I seen his equal in decisiveness in 

 investigating the most delicate things. I cannot 

 pronounce his name without such reverence as we 

 feel when we talk about the idea of the origin of 

 good. Next, Christian Pander: it has always been 

 my pride that I could give, though insignificant, 

 a push to his wonderfully illuminating investigations 

 on chick development. (p. 1). 



In § 1, entitled "The Origins of the Canine Fetus," Baer 

 gave a description of a three-week-old dog embryo, accompanied 

 by life-size illustrations (Figure 26, 7), in lOx magnification 

 from the side (Figure 26, VII a) , and in transverse section 

 (Figure 26, VII b) . The description is accompanied by a 

 comparison with the analogous stages of bird, reptilian, and 

 amphibian development. Baer also referred to Wolff's treatise 

 on the development of the intestine, to the German text of 

 Pander's dissertation, and to the work of Prevost and Dumas. 



In § 2, entitled "Primary Development of the Canine Ovum," 

 he described still earlier ova extracted from the uterus. 



Section 3 he entitled "Ovules in the Ovary of Dogs." It 

 must be noted that Baer called the early rudiment of the 

 developing embryo by the term ovum, still having a follicle 

 form. The previous section was particularly concerned with 

 those "ova." That which in modern literature is frequently 

 called the ovum-cell Baer designated by the term small ovum, 

 or ovule. First, he expressed his belief that the very 

 ovules which he observed in the oviducts and uterus could not 

 be made up from the ovary by the Graafian vesicles. He 

 considered it unlikely that very compact bodies develop in 

 the tubes as a result of coagulation of the fluid which comes 

 out of the Graafian vesicles. 



By examining the ovary with the naked eye, Baer saw in 

 the intact Graafian vesicles a pale yellowish spot which, it 

 seemed to him, swam freely in the fluid of the follicle and 

 could be disturbed by pressing with a probe. His experiences 

 are associated with the detection of the ovule, which he 



291 



