NOWLIN : THE VITELLINE BODY IN SPIDER EGGS. 289 



Lyons blue, with Gilson's fixation, makes a beautiful prepa- 

 ration. The eggs at all stages stain equally well with this. 

 I have not found any stain which shows the vitelline body 

 better. The yolk and cytoplasm take up the coloring, to be 

 sure, but the vitelline body is much more deeply stained and 

 stands out prominently. While the central sphere of the vitel- 

 line body is distinct, still the stain is not good for a study of 

 fine structures. 



For a study of mature eggs, Ehrlich's hsematoxylin alone is 

 very good. The yolk stains a uniform pale brown, while the 

 nucleus and vitelline body are much deeper. The chromatic 

 parts of the nucleus cannot be clearly distinguished, but the 

 form of the nucleus at this stage can be seen. Younger eggs, 

 even the oogonia, can be located clearly, but no careful study 

 can be made. 



Auerbach's stain, though the result varies with different con- 

 ditions of the egg, differentiates the structures very well indeed. 

 The young eggs color a delicate pink throughout. The yolk is 

 yellow in those eggs where it has begun to accumulate ; the 

 nucleus and cytoplasm, pink. In other cases Auerbach stains 

 all structures a purplish red, but even then the vitelline body 

 is easily distinguished, because it is more densely stained. 



Heidenhain's iron-hsematoxylin is the best stain for detail 

 work, as it brings out the most minute structures. Then the 

 highest powers of the microscope can be used with this stain, 

 while the diffuseness of the others makes such a thing almost 

 impossible. For a study of karyokinesis I used it exclusively, 

 and it did what the others failed to do ; that is, it showed the 

 pseudo-chromosomes, or small rods at the center of the vitel- 

 line body. It worked fairly well on mature eggs, but has the 

 disadvantage of staining the yolk very densely, which in many 

 cases cannot be bleached sufficiently for study. The thing most 

 in its favor, however, is the uniformity with which it works, so 

 that structures stained with it can readily be recognized at any 

 stage of their development. While I used many other stains, 

 I always verified my observations with this one. 



