14U W. H. LONGLEY 



a point of departure for researches upon the development of t he 

 mammaHan egg undertaken since that time. Papers by Kirk- 

 ham ('07) and Lams and Doorme ('07) have led Sobotta himself 

 to modify some of the views which he held concerning polar body 

 formation in the mouse egg. He no longer believes that only 

 10 per cent of the mature eggs of this animal form two polar bodies, 

 but agrees that its maturation processes conform to the usual 

 type. 



Other important papers upon the early development of mam- 

 malian eggs have been published by Rubaschkin ('05) upon the 

 guinea pig and O. Van der Stricht ('09) upon the bat. The last 

 paper to appear upon this subject is by Sobotta and Burckhard 

 ('10) entitled "Reifung und Befruchtung des Eies der Weissen 

 Ratte." In short, maturation has been studied thoroughly and 

 the results of the study presented in a conclusive manner in the 

 case of the bat, guinea pig, mouse and rat only. 



On account of the difficulties encountered in procuring the 

 eggs of representatives of the higher orders of mammals their 

 study has been very much neglected. These difficulties consist 

 in the less frequent periods of oestrus, the smaller number of eggs 

 discharged at one ovulation, the longer period of gestation and 

 the greater difficulty in keeping the animals and breeding them in 

 captivity. In addition by no means the least obstacle lies in 

 the larger size of the ovaries which must be prepared for exami- 

 nation. Restricted by these conditions, knowledge of the matur- 

 ation of the eggs of mammals higher than rodents is confined to 

 that contained in preliminary reports by R. Van der Stricht 

 ('08) and O. Van der Stricht ('08) upon the cat and dog respec- 

 tively and to scattered notes upon maturation distributed sparsely 

 through a great mass of literature devoted to other problems. 



In addition to describing the morphological changes in the 

 cat's egg during maturation the present paper indicates an un- 

 usual physiological condition connected with the process in this 

 animal. 



