210 ORGANS OF EEPEODUCTIOTSr. 



cles. In the latter, however, the nucleus looks rather 

 more solid. The smallest Purkinjean vesicle which I 

 saw was go^ooths of an inch in diameter. 



The yelk of the young eggs appears to possess no 

 vitelline membrane ; nor, though the boundary is 

 perfectly distinct, has it any definite shape, but, appa- 

 rently in consequence of the pressure put upon it by 

 its neighbours, the outline which it assumes is very 

 variable. As, however, it continually increases in size, 

 it gradually comes to occupy the whole width of the 

 egg-tube, and then assumes generally a more or less 

 wedge-like shape, the Purkinjean vesicle occupying 

 the thicker end. There are usually three or four egg- 

 germs in this stage. 



The two or three most advanced egg-germs approxi- 

 mated more or less to the form of the mature egg, and 

 were darkened by the deposition of granules and small 

 oil-globules. 



Below the egg was some yellow matter, correspond- 

 ing apparently to the so-called " corpora lutea" found 

 in the eof^-tubes of insects. 



The mature egg is elongated, fusiform, about -g^ths 

 of an inch in length, and enclosed in a tough, some- 

 what transparent chorion. 



The Purkinjean vesicle, which in the smallest egg- 

 germs was sometimes even less than y^^th of an inch, 

 increases to as much as y^th of an inch in diameter. 

 In the meanwhile the macula has undergone important 

 changes. 



On its first appearance it is a single, apparently 

 solid body ; but even in the smallest egg-germs the 

 Purkinjean vesicle contains very often, besides the 

 macula, a small vesicle, which increases in size with 

 the macula, but otherwise undergoes no alteration. In 

 many cases, however, I could not see this secondary 

 macula. 



The macula itself soon appears to develope in its 

 interior a clear space, which is apparently bounded by 

 a membrane, since after a time it works its way to the 



