THE EGG OF THE DOMESTIC CAT 141 



THE EGG OF THE CAT 

 Material and methods 



x\lt hough some of the material upon which this study was made 

 was furnished by animals in which the sequence of events during 

 the period of oestrus was incompletely known, practically all of 

 importance was obtained from individuals which had been for 

 a variable time under observation in captivity. It was found to 

 be quite possible to carry on breeding operations in the laboratory, 

 although Winiwarter and Saintmont ('08) state that cats will 

 not breed under restraint. It is only fair to say, however, that 

 there is great variation in the behavior of males and that, while 

 observers were present, few of those tried would act promptly, 

 or at all. In a considerable number only one was found which 

 could be relied upon to afford a final test for oestrus. This cat 

 would immediately cover, or attempt to cover, any female put 

 in with him, and her willingness or unwillingness to allow copu- 

 lation settled the doubtful point. 



There is little difficulty in deciding when copulation has been 

 effected. Occasionally, however, one finds a female, usually- 

 young, which does not give the customary response. In such 

 cases a portion of the contents of the vagina was withdrawn with 

 a fine pipette, and submitted to microscopic examination for 

 spermatozoa, which, when found under such conditions, exhibited 

 great activity. 



The ovaries of all animals killed were examined at once to deter- 

 mine whether ovulation had or had not occurred. Each recently 

 ruptured follicle was marked, by an opening, the edges of which 

 were generally, but not always, red, rough and swollen to form 

 a characteristic elevation. Within the space of three or four 

 days the irregularity disappears, the elevations become more or 

 less conical, and blood vessels are very plainly visible near the 

 surface of the newly organized tissue. The mature unruptured 

 follicles are large, convex, smooth and semi-transparent. 



The only difficulty in telling in advance how many eggs should 

 be found in the tube arises from the fact that sometimes two rup- 

 tured follicles are very close to one another, and that occasionally 



