III. — Maturation of the Egg of the White Mouse. 

 By William B. Kirkham. 



Table of Contents. , 



I. — Literature relating to the Mam- II. — The Egg, etc. — Continued. 



malian Ovum. First Polar Body. 



II. — The Egg of the Mouse. ^ Ovulation. 



Material and Method. Fertilization. 



Breeding Season. Second Polar Body. 



Mature Ovum. III. — Summary. 



First Polar Spindle. IV. — Bibliography. 



I. — TAterature relating to the Mammalian Ovum. 



So far as known, the first person to discover the cleavage stages 

 in any mammalian egg was R, de Graaf (i678), and subsequent to 

 his researches no further investigations in this line are met with 

 until 1797, when an Englishman, William Cruikshank, published 

 "Experiments in which," to quote the quaint title, "on the third 

 Day after Impregnation, the Ova of Rabbits were found in the fal- 

 lopian Tubes ; and on the fourth day after Impregnation, in the 

 uterus itself ; with the first Appearances of the Foetus." Cruik- 

 shank noted some rabbit's eggs before cleavage, a few at the two- 

 celled stage, and some very young embryos. 



The discovery of the ovarian eggs of mammals was made by K- 

 E. von Baer ('27, '28), who also observed some cleavage stages in 

 eggs of the rabbit, dog, and pig. However, the study of mammalian 

 cytology, as such, maj^ be said to date from the work of an English 

 doctor, Martin Bany, who, in 1838-39, published two papers in the 

 Philosophical Transactions of the Royal Society of London, the 

 first dealing with the ovarian eggs of rabbits, and the second with 

 the growth and discharge of these eggs from the ovar}^ Bany 

 figures ovarian eggs of various animals, including not only the 

 rabbit, but the hog, sheep, ox, dog, cat, and tiger, having been 

 presented with some ovaries of the last-named animal by the com- 

 parative anatomist, Richard Owen. He found that the time of ovu- 

 lation varied in the rabbit, but is commonly from 9 to 10 hours after 

 copulation. 



Then follows a series of investigations on the eggs of the rabbit, 

 dog, guinea-pig, and deer, by Bischoff ('42, '45, '52, '54). This 

 worker was the first to announce that fertilization consists of a physi- 



Trans. Conn. Acad., Vol. XIII. 6 August. 1907. 



