524 EDMUND NEWTON HARVEY 



the color change of neutral red. The yellow color returns to 

 some extent on standing. Both Arbacia and Asterias eggs stain 

 in 100 cc. sea water + 2 cc. -fs HCl but fail to stain if 3 cc. to 

 HCl is added, even after one hour. They are quite transparent 

 and uncoagulated. About half the egg of Asterias coagulate in 

 100 cc. sea water + 5 cc. fn HCl after one hour's time and 

 those which are opaque and coagulated become faint pink in 

 color. Apparently the dye is adsorbed by the proteid coagulum. 



The mechanism of absorption of neutral red is practically the 

 same as in Paramoecium. In all the eggs thus far studied (Cum- 

 ingia, Arbacia, Asterias, Toxopneustes, Hipponoe, Holothuria 

 and Chaetopterus) it combines with very definite granules which 

 often differ in color, always in specific gravity and generally in 

 size, from other granules in the egg. In markedly pigmented 

 eggs like Arbacia or Cumingia, it is the pigment granules which 

 become stained, but in the eggs of Holothuria, the large yolk 

 granules are orange and the dye absorbing granules are small and 

 colorless. The latter are much the heaviest granules present and 

 pass to the outer pole of the egg when centrifuged. That this is 

 not due to an increase in weight from taking up of the dye may be 

 shown by first centrifuging the eggs and then staining them. 

 Exactly the same areas stain as if the experiment had been re- 

 versed, the eggs first stained and then centrifuged. 



The two statements made above are true of all the eggs studied 

 except Chaetopterus. The stainable granules of Chaetopterus 

 are specifically different from other granules in the egg, but they 

 are not the heaviest. The difference is best made clear by refer- 

 ence to figs. 2 and 3. 



The red area is found to be just under the oil and to consist of 

 globules of varying size which have apparently been formed by 

 fusion of very minute red granules. These may be easily seen 

 over the clear area and scattered throughout the yolk mass, giving 

 a pinkish tinge to that region. 



A similar aggregation of minute granules to form larger granules 

 occurs in Toxopneustes also. Both fertiUzed and unfertilized 

 eggs at first stain 'diffusely,' i.e., the dye is locahzed in very minute 

 granules, visible under high magnification. More and more of 



