No. 2.] THE OVARIAN EGG OF LIMULUS. i6l 



In eggs that have been discharged from the follicle into the 

 ovarian tube no trace of the nucleolus could be observed. The 

 last phases described seem to be stages of final dissolution, and 

 absorption of the nucleolus. It seems that the discharge of the 

 egg from the follicle marks its end, as the entrance of the egg 

 into the follicle marked its beginning. Its history coincides 

 with that period of growth of the egg in which the latter 

 remains in organic connection with the parent organism. This 

 would seem to associate it with the phenomena of nutrition and 

 growth of the egg. 



There are cases also, in this period of growth, in which there 

 is no nucleolus in the germinal vesicle. Such cases occur when 

 the germinal vesicle is surrounded by a zone of deeply staining 

 granules, which resemble chromatin granules in their behavior 

 towards haematoxylin and carmine stains (PI. XIV, Fig. 29). 

 Whether this is an abnormal condition, I cannot say. The 

 appearances will be discussed more fully in connection with the 

 cytoplasm. We have seen, also, that at the beginning there 

 may be two similar nucleoli (PI. XIV, Fig. 26), while later one 

 of these has disappeared. In the second stage of the egg 

 two nucleoli are rarely observed. But we have seen that 

 towards the end, when the nucleolus has greatly degenerated, 

 there may be a second smaller one apparently having recently 

 arisen. 



In view of these facts, together with its great variability, it 

 is safe to say that it is not a permanent organ. 



The appearances described above seem to show that the 

 nucleolus is not simple, but composite. It consists of a 

 framework of linin similar to that of the germinal vesicle, and 

 a more or less homogeneous, semi-solid, stainable mass, which, 

 accumulating at the nodes of the linin network, flows together 

 into a spherical body, enclosing portions of the linin fibers. 

 Within this mass chemical changes appear to take place which 

 ultimately result in a substance resembling the yolk of the ma- 

 ture egg, and which, like it, assume the form of spherical refrac- 

 tive bodies. These when formed are extruded and give rise 

 to " Nebennucleoli." The chemical or other processes within 

 appear to continue ; and the nucleolus, losing substance from 



