Relation betzveen Nucleolus and Chromosomes. 43 



trustworthy clue as to the manner of the reduction of the chromosomes. 

 The slight evidence that synizesis and the maturation divisions give seems to 

 indicate that Asterias forbesii agrees with the parasynaptic type of reduction. 



Up to the period when the oocyte has reached about half its full-grown 

 size the cytoplasm is wide-meshed and coarsely granular, the granules 

 usually lodging at the intersections of the meshwork. With the iron hema- 

 toxylin and orange G combination of stains, the cytoplasm stains dark blue 

 or in cases where the staining action of the orange G is prolonged the 

 resulting stain is dark brown. In subsequent stages the cytoplasm is always 

 stained a lighter or darker orange color. This difference in color reaction to 

 similar staining combinations between the cytoplasm of the growing and full- 

 grown oocyte is very striking and due, I believe, to the presence of a great 

 amount of yolk or to the fore-products of chromatin formation in process of 

 transportation to the nucleus and nucleolus. There is a progressive and 

 approximately proportional increase in volume of nucleolus, nucleus and cell- 

 body through the growth-period. 



Auerbach's stain reveals a similar difference in staining reaction be- 

 tween the cytoplasm of the growing and that of the full-grown oocyte. 

 In the latter the cytoplasm has a deep-red (fuchsin) color, while that of the 

 smaller oocytes has a grayish or bluish-red color, showing undoubtedly the 

 influence of the methyl green constituent of the stain in its reaction to the 

 forming- chromatin. Similar observations have been reported by Griffin in 

 the case of the egg of Zirphcea. 



The ovaries upon which the above observations are made were gath- 

 ered during July and August. A study of ovaries gathered during the last 

 week in December confirmed in every respect the description given above of 

 ovarian material. In both cases the sparsity of transition stages and the large 

 number of apparently full-grown oocytes is very striking. It appears that 

 Asterias has no special periods of reproductive activity, as is the case with 

 most of the Metazoa, but produces ripe eggs perpetually. 



THE FULL-GROWN PRIMARY OOCYTE. 



The full-grown primary oocyte of spherical outline has a diameter of 

 about 100 microns. The nucleus of such an oocyte has a diameter of from 

 one-half to somewhat less than one-half the diameter of the cell (5040 

 microns). The nucleolus varies in size from one- fourth to one-fifth the 

 diameter of the nucleus. The nucleolus (or germinal spot) invariably takes 

 an eccentric position as regards the germinal vesicle (figs. 37, 38, 39). A 

 generalization to this effect for many kinds of eggs was made by Mont- 

 gomery in 1898. The eccentricity of the nucleolus showed no regularity in 

 respect to any particular side of the nucleus or even to the wall of the 

 alveolus (figs. 38, 39). The nucleus also often holds an eccentric position 

 as regards the egg-cell, though not infrequently it is located centrally (figs. 



