MONOGRAPH OF THE EXISTING CRINOIDS. 381 



The nucleolar vacuoles, even when they reach a considerable size, never cause 

 the slightest projection on the surface of the nucleolus, nor has Professor Chubb 

 ever seen any other indication that they discharge their contents to the exterior. 

 The appearance of the faintly staining region, on the other hand, is frequently 

 such as to suggest that a discharge from it into the caryolymph is taking place. 

 Thus, wherever the faintly staining area comes to the surface it causes a slight but 

 distinct projection. In no case, however, do appearances ever suggest that the 

 acidophile substance of the faintly staining area is itself discharged. 



In the adult egg an extensive faintly staining area is always present, and its 

 form and position almost invariably suggest that a discharge is taking place from 

 it — a suggestion which is greatly intensified by the almost invariable presence 

 in the caryolymph of deeply stained spherules so placed as to appear as if recently 

 discharged as a stream from that region of the nucleolar surface to which the 

 faintly staining area most closely approaches. Occasionally the faintly staining 

 area approaches the surface of the nucleolus at more than one point ; in such cases 

 it is common to find spherules in the caryolymph in relation to each such point. 

 It is only rarely that such spherules are found in the nucleus which do not show 

 this spatial relation to the nucleous; and when such spherules do occur they are 

 always more or less isolated in position and few in number. 



The mode of origin of these spherules as a discharge from the faintly staining 

 area of the nucleolus, which their arrangement irresistibly suggests, is still further 

 indicated by the appearance presented by the nuclei figured by Professor Chubb. 

 In each of these a spherule, similar to those in the caryolymph, is seen in the center, 

 not of the destained area, but of one of the vacuoles in the cortical region. Another 

 figure shows a deeply basophile spherule identical with those in the caryolymph 

 immediately outside the faintly staining area of the nucleolus, but lying in a vacuole 

 within the substance of the cortical region and, by reason of its intensely basophile 

 character, standing in striking contrast to it. 



These spherules, like the substance of the nucleolus itself, are equally well 

 fixed with all reagents and, like, the cortical substance of the nucleolus, are nearly 

 always deeply stained. Their staining reactions, however, do not exactly corre- 

 spond with those of the cortical substance, for when, as frequently happens in the 

 older eggs after Hermann fixation, the cortical substance of the nucleolus is de- 

 stained to a faint brown, the discharged spherules in the same egg are usually 

 deeply basophile. In size these nucleolar spherules often equal the peripheral 

 spherules, with which they also agree in showing a much greater range of variation 

 than do the yolk spheres proper. 



Similar spherules, presenting the appearance of having been recently discharged 

 from the nucleolus, are also occasionally, though much more rarely, to be found in 

 the growing oocyte. 



The fact that this appearance of a discharge of spherules from the nucleolus 

 should be so rarely seen in the growing oocyte admits of very simple explanation. 

 In the growing egg the intermittent discharges must be separated from one another 

 by a considerable interval, while the time occupied by the actual discharge must be 

 very brief. The chances, therefore, against the moment of discharge coinciding 



