Xncleoli during- the Oog-euesis of the Draoon-Hy. 219 



iiucleolns. they become smaller and more irregular in outline (Fiff. 14 

 and 25): second, although they are being formed throughout the 

 entire growth period, as is shown by the fact thay they can be 

 seen passing out of the basiphile nucleolus throughout the entire 

 length of the egg-string, yet there are never more than four or five 

 in the nucleus at one time and more often only one or two. 



I think there can be no doubt that both kinds of nucleoli are 

 of a liquid or viscid nature. This is shown in the basiphile nucleoli 

 by their tendency to become vacuolated (Fig. 26, 28, 34, 35 and 38), 

 while Fig. 21 and 27 prove quite conclusively that the oxyphile 

 nucleolus is liquid, for as it passes out of the basiphile nucleolus 

 the pressure on the sides of the droplet causes it to elongate. 



Accompanying the tbrmation and solution of the oxyphile nucleolus, 

 a large amount of chromatin appears in the nucleus and is de- 

 posited in strings of granules along the linin reticulum. It will be 

 remembered that in the early growth period practically all of the 

 chromatin is in the nucleolus. Now, however, a coarse granular 

 reticulum of chromatic material is laid down, and one is tempted to 

 conclude that this chromatin is derived in large part from the oxy- 

 phile substance in solution in the nuclear sap, the reverse chemical 

 process taking place with the result that the soluble para-nuclein is 

 converted into insoluble nuclein. Good evidence for this lies in the 

 fact that, as the oxyphile nucleolus dissolves, rows of chromatic 

 granules are found radiating from it (Fig. 22—27). 



(b) Yolk-nuclei. 



As the chromatin is being laid down in the nucleus, there is a 

 rapid increase in the size of the yolk-nucleus, and as the rapid 

 growth of the two occurs at the same time, with nothing but the 

 nuclear wall separating them and as the granules of the yolk-nuclei 

 take the chromatin stain, it seems probably that the chromatin may 

 have something to do with the formation of the yolk-granules. In 

 no instance could chromatin granules be seen passing through the 

 nuclear wall into the cytoplasm, as has been described by many 

 writers, and, therefore, if nuclear material enters the cytoplasm the 

 transfer must take place in solution. 



Soon in the growth period, the yolk-nuclei break away from 

 the nuclear wall, separate into several masses and scatter throughout 

 the cytoplasm (Fig. 14, 19, 22, etc.). 



