BEHAVIOR OF ANURA TOWARD COLLOIDAL DYES / 19 



6) In another individual of this same experiment which had 

 remained in the dye solution for twenty hours and fifteen minutes, 

 a few of the lymphatics of the caudal fin appeared to be more 

 deeply stained by the dye, than in the larva above-mentioned. 

 The liver and mesonephros were removed from the body and the 

 liver sectioned. No definite traces of dye granules were observed 

 in the stellate cells of the liver, but a few mononuclear leucocytes 

 containing dye granules were found in its capillary vessels. A 

 teased preparation of the kidney showed that the dye had been 

 stored in the epithelium of a few tubules, and mononuclear cells 

 containing dye granules were also present in the intertubular 

 tissue. 



These two individuals by no means represent the average con- 

 ditions observed in the entire lot of larvae concerned hi this 

 experiment. They were chosen from the lot solely on account of 

 the presence of dye which was observed in the lymphatics of the 

 caudal fin. In none of the other larvae of this experiment were the 

 lymphatics of the caudal fin stained by the dye when the above 

 observations were made. After a short immersion in dye, larvae 

 which may appear slightly bluish in color are more liable than 

 others to have dye granules stored in their tissues. 



Experiment 7. Similar observations were made on unidentified 

 species of advanced frog larvae which were brought into the 

 laboratory during July and August. 



a) Frog larvae averaging about 20-22 millimeters in length, 

 were placed in a 1 : 1000 solution of trypan blue on August 10. 

 After sixteen and one-half hours immersion in the dye solution, 

 the liver and mesonephros were removed from one of the larvae 

 in which a doubtful trace of dye was observed in one of the 

 lymphatics of the caudal fin. A study of serial sections of the 

 liver and mesonephros showed that no dye had been stored in the 

 stellate cells of the liver, or in the epithelium of the tubules in the 

 mesonephros. A few mononuclears containing dye granules were 

 found, however, in the liver capillaries and in the intertubular 

 tissue of the kidney. The mononuclears found in the liver were 

 more deeply stained than those in the kidney. 



