i88' 



THE AMERICAN NATURALIST. [Vol. XXXVIII. 



be not far from the surface 12 hours after the eggs are laid, 

 while 24 hours after laying the cleavage nuclei are near the 

 centre of the egg and only about ten in number. 



There are only a few cleavage nuclei half way out to the 

 surface 48 hours after laying, while 72 hours shows a large number 

 of nuclei near the surface. 



In the live eggs some of the cleavage phenomena may be seen 

 with a pocket lens and are much as described by Herrick for 

 C. ininumis. At about 72 hours there are rounded areas scat- 

 tered all over the egg, shimmering through the outer part of the 

 egg ; each is about 1 5 /x in diameter and some 30 of them may 

 be seen upon any face of the egg. When such eggs are crushed 

 under the microscope the dense, clear nuclear areas may be 

 found amongst the yolk spherules and also long bundles of fibres 

 connecting the chromatin bodies. 



Eggs taken at earlier times from different females differed 

 and also upon the same female. At about 48 hours a few 

 clear areas might be seen in a group deep within the sub- 

 stance of the egg ; some eggs showed 5 or 6, some 30-40, 

 some none at all. Later there were similar areas nearer the 

 surface but upon one side of the egg only. Soon these areas 

 spread so that but part of the surface of the eggs failed to 

 show them and finally they are all over the egg. 



After the end of the 3d day the increase of these areas by 

 division is plainly indicated by their shape. From 82 hours 

 on to 7 days there are some hundreds of areas each about 

 1 50 to 300 /X, some elliptical, others dumb-bell shaped and others 

 in pairs of rounded areas 150 /x. in each diameter. There is 

 now a very striking appearance as of light beads floating above 

 the dark background of the egg yolk. As the areas increase 

 in number they become crowded till they finally touch one 

 another and now in profile stand up as hillocks bounded by val- 

 leys and projecting into a space of some 100 /x that is formed 

 between the egg and its case. 



In late cleavage the color of the egg, which is olive or yellow 

 green at first but varies much in different females, is now 

 more dark sage green and this color with the clear space about 

 the egg gives the entire mass of eggs upon the female a more 



