No. 2.] THE OVARIAN EGG OF LIMULUS. 159 



I see no reason why this may not be regarded as a so-called 

 " Nebennucleolus." The difficulty with which these bodies 

 stain seems to correspond to the condition of bodies described 

 under that name by various authors. 



Besides this single body extruded in this way, it can some- 

 times be seen that the central cavity of the " Hauptnucleolus " 

 is filled with a number of comparatively large spherical bodies 

 that behave toward stains similarly to the one just described 

 (PL XIII, Figs. 4, 8). In one case an opening in the thinnest 

 part of the "Hauptnucleolus" was observed; and some of 

 these internal bodies appeared to be on the point of being 

 extruded (PI. XIII, Fig. 4). One was lying at the opening 

 outside the " Hauptnucleolus," and another just inside ; the 

 rest of the internal cavity was occupied by several of these 

 bodies. They were surrounded by a finely granular substance 

 which was strongly contrasted with the outer zone, this being 

 very thin, but staining deeply. 



I cannot say that all " Nebennucleoli " originate in this way. 

 Occasionally one may be seen partly imbedded in the outer 

 zone of the " Hauptnucleolus," and this may occur at any 

 point where the outer zone is thickest. 



Similar bodies are found distributed throughout the germinal 

 vesicle (PI. XIII, Fig. 15). In the living egg they appear as 

 shining vesicles, often occupying diverticula of the germinal 

 vesicle. They can also occasionally be observed in the cyto- 

 plasm of the living egg (PI. XIII, Fig. 3 ; PI. XVI, Fig. 112). 

 As I have never seen them actually pass out from the germinal 

 vesicle, I cannot say that they do so. 



If the living egg is ruptured, and the contents made to flow 

 out, they can be seen still within the germinal vesicle, and also 

 in its neighborhood. 



On a closer examination they are seen to be vesicles, con- 

 sisting of a delicate membrane, within which are a number of 

 granules, apparently suspended in a liquid. This can be made 

 to flow out when the membrane is ruptured. 



The " Hauptnucleolus " increases as the egg increases in 

 size, and, in the third stage of the egg, may often reach gigan- 

 tic proportions (PI. XIII, Fig. 5 ; PI. XVI, Figs. 104, 114). It 



