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Researches in Embryology. Second Series. By Martin 

 Barry, M.D., F.R.S.E., Member of the Wernerian Natural 

 History Society, Fellow of the Royal College of Physicians 

 in Edinburgh. - 



The author having, in i)a& first series of these researches, 

 noticed at pp. 203, 4, and 5, of A^lunie xxvi. of this Journal, 

 investigated the formation of the mammiferous ovum, de- 

 scribes, in a second series, read before the Royal Society of 

 London, its incipient development. The knowledge at present 

 supposed to be possessed of the early stages in the develop- 

 ment of that ovum, consists chiefly of inferences from observa- 

 tions made on the ovum of the bird. 



But there exists a period in the history of the owcai of the 

 mammal, regarding which we have hitherto scarcely any direct 

 or positive knowledge. It appeared, therefore, highly desir- 

 able to obtain a series of observations in continuous succession 

 on the earliest stages of development. In conducting this in- 

 vestigation, the author piu-posely confined his attention to a 

 single species, namely, the rabbit, of which he examined more 

 than a hundred individual animals. Besides ova met with in 

 the ovary, apparently impregnated, and destined to be dis- 

 charged from that organ, he has seen upwards of three hun- 

 dred ova in the Fallopian tube and uterus ; very few of the 

 latter exceeding half a line in their diameter. The results of 

 these investigations have compelled the author to express his 

 dissent from some of the leading doctrines of embryology, 

 which at present prevail, as respects not only the class Mam- 

 malia, but the animal kingdom at large. The following are 

 the principal facts which the author has observed in the de- 

 velopment of the mammiferous ovum. 



The difference between the mature and imraatm-e ovum 

 consists in the condition of the yelk ; the yelk of the mature 

 ovum containing no oil-like globules. Both maceration and 

 incipient absorption produce changes in the unimpregnated 

 ovum, M'hich, in some respects, i-esemble those referable to 

 impregnation. During the rut, the number of Graafian ve- 

 sicles appearing to become prepared for discliarging their ova, 



