BEHAVIOR OF ANURA TOWARD COLLOIDAL DYES 43 



Experiment 21 . Three larvae of Diemyctylus measuring about 

 forty-five millimeters in length were placed in solutions of trypan 

 blue (1 : 1500, 1 : 2000 and 1 : 1000) on July 12 and were killed on 

 July 16, 22 and 27, respectively, Not a trace of dye was observed 

 in sections of the liver and mesonephros of those killed on July 

 16 (4 days in dye) and July 22 (10 days in dye), or in the meso- 

 nephros of the individual killed on July 27 (15 days in dye). In 

 the liver capillaries of the latter, however, but not in the cyto- 

 plasm of the stellate cells, a bluish precipitate of the dye solu- 

 tion was observed. 



If we may judge from the results of feeding experiments, above- 

 mentioned, this dye did not gain admission to the body through 

 the integument, but reached the liver by way of the intestinal 

 mucosa and portal vein. 



11. ON THE CAUSES WHICH UNDERLIE THE INITIATION OF THE 



PROCESS BY WHICH DYE GRANULES ARE STORED IN THE 



CYTOPLASM OF CERTAIN TYPICAL CELLS OF THE 



EMBRYO 



Experiments have shown us that the initiation of the process by 

 which dye granules are stored in the cytoplasm of the cell is 

 associated with the attainment of a distinctive ontogenetic larval 

 stage. It is therefore of interest to inquire still further what these 

 ontogenetic conditions actually may be. 



When toad larvae are placed in solutions of colloidal acid dyes 

 on the third and fourth days after fertilization, we have seen that 

 visible signs of dye granules are not ordinarily found in the cell 

 until the ninth day after fertilization. As some time always 

 elapses when larvae are placed in solutions of colloidal acid dyes 

 before dye granules appear in the cytoplasm of the cell, we must 

 look for some stage of development prior to the ninth day at 

 which the process of ingestion or absorption of dye particles is 

 actually initiated. 



It is evident that the storage of dye particles by the cytoplasm 

 of the cell cannot possibly take place until the celHs brought into 

 contact with the dye solution. When dye solutions gain entrance 

 to the body through the integument it would therefore be essen- 



