INCLUSIONS IN EGG OF ECHINARACHNIUS 477 



more spongy and vacuolated cytoplasm than the earlier stages 

 of the series, which indicates a loss of some substance. Figures 

 16 and 17 show a similar phenomenon in modified Bouin material. 

 Therefore, these plates are of a nutritive character and are used 

 up by the cell during processes of development. 



They contain a certain amount of fat, as is shown by staining 

 with Sudan III. Fifteen minutes' staining with alcohoHc sudan 

 III gives them a very decided salmon-pink color. After soaking 

 for twenty-four hours in oil of turpentine, the sections stained in 

 Sudan III gave no color whatever, even when the stain was 

 allowed to act for thirty minutes. There was evidently some fat 

 there which was removed by the turpentine. After treatment 

 with turpentine the plates retained their characteristic form and 

 appearance except that they lacked the capacity to take up sudan 

 III. The nutritive plates are probably of complex chemical 

 structure. 



While the nutritive plates do not in all cases behave like yolk 

 with regard to staining reactions, yet their obvious function and 

 their shape and distribution point to the conclusion that they 

 must be yolk. 



From their method of origin these yolk plates may be linked up 

 with the other cell inclusions. This point will be considered 

 after the discussion of mitochondria. 



B. Living inclusions 



Mitochondria. In addition to the above deutoplasmic in- 

 clusions, there are also active, living constituents which are dis- 

 tinct from the ground cytoplasm. These are the mitochondria. 

 The stain which differentiates them most successfully from other 

 cell inclusions is Benda's alizarin and crystal violet. They show 

 up a deep violet against a background of neutral pink. Iron 

 hematoxylin blackens them, but it also blackens other cell 

 granules. With basic fuchsin and methylene blue they are red, 

 with safranin they are red. It is possible to demonstrate mito- 

 chondria after fixation in Flemming, Flemming without acetic, 

 Meves, Champy, and modified Bouin. They are not found 



