28 CHAELES F. W. McCLURE 



subjected to solutions of high concentration. The amount of dye 

 stored in the tissues of these two larvae is relatively large, so that 

 the storage of dye particles must have begun soon after their sus- 

 pension in the dye solution. 



Experiment 12. Compare with Experiments 6, 7, 8 and 9. 

 (Partial immersion of year-old larvae of R. catesbiana in solutions 

 of colloidal acid dyes). 



a) The tail of a year-old tadpole of R. catesbiana was suspended 

 for one-half hour in a 1 : 100 solution of trypan blue in the morning 

 and afternoon of July 23, and the tadpole killed in the morning 

 of July 24. Sections were made of the liver and mesonephros. 

 Not a trace of dye was observed in the liver. Certain tubules of 

 the mesonephros were stained a light blue, in the epithelium of 

 which a few dye granules were occasionally met with. A few 

 mononuclear cells containing dye granules were also observed in 

 the intertubular tissue of the mesonephros. 



6) The tail of a year-old tadpole of R. catesbiana was suspended 

 twice daily for one-half hour on July 23 and 24, in a 1 : 100 solu- 

 tion of trypan blue and the tadpole killed in the morning of July 

 25. Sections were made of the liver and mesonephros. Dye 

 granules were found in a number of the stellate cells of the liver, 

 and large mononuclears containing dye granules were also < b- 

 served in the liver capillaries. A number of tubules in the meso- 

 nephros were deeply stained and dye granules were abundant in 

 their epithelium. Numerous deeply stained large mononuclear 

 cells were also found in the intertubular tissue of the meso- 

 nephros. 



c) The tail of a year-old tadpole of R. catesbiana was suspended 

 twice daily for one-half hour on July 20, 21 and 22 in a 1:100 

 solution of trypan blue and the tadpole killed in the morning of 

 July 23. Sections were made of the liver, mesonephros and spleen. 

 Dye granules were found in a number of the stellate cells of the 

 liver and in the epithelium of several of the tubules in the meso- 

 nephros. Deeply stained mononuclear cells were abundant in the 

 intertubular tissue of the mesonephros and a few more lightly 

 stained ones were found in the spleen. 



