46o MONTGOMERY. [Vol. XV. 



duce one or a few large vacuoles, but as to produce an irregular 

 canicular network of vacuolar substance in the nucleolus (Figs. 

 272-277, 279-281). This process often goes so far that in the 

 largest nucleoli the deeply staining ground substance may 

 appear in the form of a skein of threads, or merely of scattered 

 granules surrounded by vacuolar substance. Especially on 

 preparations stained by the Ehrlich-Biondi method is the skein- 

 like arrangement of the ground substance well marked. I 

 have no doubt that it was the observation of similar nucleoli in 

 like stages which led Carnoy to the assumption of a " nucleole- 

 noyau," that is, a nucleolus with a limiting membrane, and 

 containing a wound thread of chromatin ; it is probable that 

 Carnoy mistook the reticulum of the true ground substance of 

 the nucleolus for chromatin, and considered what is really vacuo- 

 lar substance to be the original ground substance ; only 

 studies on the genesis of a nucleolus can explain its various 

 components. 



In the largest ova found in the body cavity the nucleolus 

 reaches its maximum size (Figs. 279-281). It contains a greater 

 amount of vacuolar than of ground substance, and instead of 

 being regularly oval, as it was before, is often quite irregular 

 in form, and very frequently apposed to the nuclear membrane 

 (a position not noticed in any of the preceding stages). Whether 

 this irregularity of form denotes the commencement of a degen- 

 eration of the nucleolus I cannot say, since I had no prepara- 

 tions of the stages of reduction. 



Two nucleoli were found in only two germinal vesicles (Figs. 

 262 and 266), and in a spirem stage of an ovogonium three small 

 nucleoli were present in one nucleus (Fig. 261). In the hun- 

 dreds of other resting nuclei examined a single nucleolus was 

 invariably present. These exceptional cases must, therefore, 

 be considered abnormal, and not typical for certain stages of 

 the nucleus. 



In the larger germinal vesicles there is a peculiar body in 

 contact with the nucleolus, which remains to be described. 

 This body («.r., Figs. 272, 274-277,279, 281) is homogeneous, 

 somewhat refractive, and lies either in close contact with the 

 surface of the nucleolus, projecting beyond the periphery of the 



