42 CHABLES F. W. McCLURE 



b) The tail of a large tadpole of R. catesbiana was suspended for 

 short intervals daily from December 24 to December 28, inclu- 

 sive, in a freshly-made 1 : 100 solution of Niagara blue and killed 

 on December 29. The actual length of time the tadpole was sus- 

 pended in dye during a period of five days was two hours and 

 forty-five minutes. During this experiment the tadpole was kept 

 in a cool room of which the temperature averaged about 10C. 



The merest trace of dye was stored in a very few of the stellate 

 cells of the liver and only a very small amount was present in the 

 epithelium of the kidney tubules. Not a trace of dye was ob- 

 served in the spleen or in the mononuclears present in the inter- 

 tubular tissue of the kidneys. 



These experiments might indicate either that dye solutions do 

 not gain admission to the body as readily during the season of 

 hibernation as during the Spring and Summer, or, if they do, 

 that the tissues do not as readily react toward the dye. 



If we compare these experiments with essentially similar ones 

 made during the Spring and Summer (Exp. 8 and 12) it is evident 

 that the reactions of the tissues toward the dye during the season 

 of hibernation are in general decidedly less pronounced. In 

 'only one instance was dye found to be really noticeably pres- 

 ent in the liver and kidneys (Exp. 19 c). In two experiments 

 its absorption wholly (Exp. 18 and 19 a) by the intestinal 

 mucosa may have occurred. In both of the experiments (Exp. 

 20 a and 20 b) in which only the tail was immersed in the dye, 

 the aniQunt of dye stored in the kidney was more pronounced 

 than that stored in the liver. Although these experiments 

 clearly indicate that colloidal acid dye solutions do pass through 

 the integument during the season of hibernation, there also appears 

 to be a lack in the ability of certain recognized tissues to react 

 toward the dye at this time. In other words, cells which ordi- 

 narily sto,re the dye during the Spring and Summer appear to 

 have become wholly or partially inactive toward the dye during 

 the Winter months. 



It is interesting to compare the behavior of advanced larvae 

 of Diemyctylus viridescens toward solutions of colloidal acid 

 dyes with those of Rana last mentioned. 



