BEHAVIOR OF ANURA TOWARD COLLOIDAL DYES 41 



the tubules in the kidney. No mononuclears containing dye 

 granules were observed. 



6) A large tadpole of R. catesbiana was placed in a freshly- 

 made 1:1000 solution of Niagara blue on November 23 and 

 remained in the same until November 28, when it was killed (5 

 days in dye). 



Not a trace of dye was stored in any cell of the liver, kidney or 

 spleen. 



c) A large tadpole of R. catesbiana was placed in a freshly- 

 made 1 : 1500 solution of Niagara blue on December 2 and re- 

 mained in the same until December 8, when it was killed (6 

 days in dye). 



Dye granules were stored in the epithelium of a number of 

 tubules in the kidney and also to a much less extent in the stellate 

 cells of the liver capillaries. Not a trace of dye was observed in 

 the spleen. No mononuclears containing dye granules were 

 found in the intertubular tissue of the kidneys. A number of 

 large cells, however, probably mononuclear leucocytes, were 

 found to be in an active state of division in the intertubular tissue 

 of the kidneys. Similar cells were occasionally found in the liver 

 and spleen. These cells were unstained. 



Experiment 20 (compare with Experiment 12, p. 28). a) The tail 

 of a large tadpole of R. catesbiana was suspended for short inter- 

 vals daily from December 8 to December 11, inclusive, in a 

 freshly-made 1 : 100 solution of trypan blue, and killed on Decem- 

 ber 13. The actual length of time the tadpole was suspended in 

 dye during a period of five days was one hour and fifteen minutes. 



The tadpole presented no external evidence of being stained 

 by the dye except on the abdomen. This tadpole possessed two 

 accessory spleens. 



A mere trace of dye was stored in the stellate cells of the liver 

 and a few dye granules were found in the epithelium of some of the 

 tubules in the kidney. Not a trace of dye was observed in the 

 spleen. No mononuclears containing dye granules were found in 

 the intertubular tissue of the kidney. Large mononuclears in an 

 active state of division, as observed in Experiment 19 c, were 

 found in the intertubular tissue of the kidneys. 



