of the Development of the Ovum of the Rabbit. 43 



consists of cells : which indeed are represented in two of Bis- 

 chofPs figures (figs. 8 and 9). 



Formation of' the Ovum. — No one on reading p. 19 of Bis- 

 choff's book would suppose that the formation of the ovum 

 had ever been described : still less would it be imagined that 

 the writer was confirming observations recorded four years 

 before. But I ask the reader to compare in detail BischofF's 

 figs. 10 to 13 with about twenty of my own in Plate 5. Phil. 

 Trans. 1838; and more especially BischofF's fig. 10 with my 

 figs. 2, 3, and 19, in that same plate: a stage being there re- 

 presented which he actually says (p. 19) I "overlooked" 

 [Stages still earlier than this will be found represented in a 

 paper of mine "On the Corpuscles of the Blood," Phil. Trans. 

 18*1, plate 25. figs. 164—173, and described § 188—195. 

 It is there stated that the vesicle called by me the ovisac, with 

 the whole of its contents, arises out of a body having precisely 

 the same appearance as a mammiferous young blood-disc, — 

 this blood-disc, as I have shown, being originally elliptical and 

 not round : the outer part dividing into minuter discs, which, 

 forming cells, coalesce to produce the membrane of the ovisac. 

 The germinal vesicle has previously been formed out of the 

 central portion of the disc] 



Misstatements. 



Bischqff", p. 14. — What I said regarding the changes in 

 the germinal spot, was obviously meant to apply to its condi- 

 tion as preparing for fecundation, and I headed the paragraphs 

 "preparatory changes in the germinal vesicle and germinal 

 spot." Yet BischofF makes it appear as if my description had 

 been intended to apply to the state of the germinal spot as 

 usually found. 



Bischoff p. 4. — I never attempted to show that my "reti- 

 nacula" were the analogue of the chalazae; but, on the con- 

 trary, showed that they could not be so regarded. (See my First 

 Series on Embryology, /. c. f § 92.) 



Bkchoff, p. 49. — My observations on the time taken by the 

 ovum of the Rabbit to pass through the Fallopian tube, are 

 not correctly stated. A table (my " Third Series," I. c, p. 565) 

 shows that, 230 ova having been found by me in the tube, 

 some of them had been met with there as early as the tenth 

 hour, and others as late as the seventy- second hour post co'i- 

 tum. — In the same page (p. 565 of my "Third Series") will 

 be found also the following words : " It will be seen from these 

 Tables, that ova have been found in the Fallopian tube as 

 late as 72 hours, and in the uterus as early as 52 hours post 

 co'itum." 



