BEHAVIOR OF ANURA TOWARD COLLOIDAL DYES 



29 



TABLE 7 

 Partial immersion of body of adult frogs in solutions of colloidal acid dyes 



Numerous other experiments of this character were made on 

 year-old tadpoles of R. catesbiana which leave no room for doubt 

 that solutions of colloidal acid dyes can gain entrance to the body 

 through the integument. 



In other experiments the treatment of short immersions of the 

 tail was extended over a period of seven, eight, nineteen, twenty- 

 two and even seventy-five days. In the latter case the tail was 

 suspended twice daily in a 1:100 solution of trypan blue, only 

 between July 20 and July 26, and the tadpole killed on October 

 4. Although over two months had elapsed between the last 

 treatment and the date of killing, dye was found in abundance 

 stored in typical cells of the body. 



Experiment 13 (table 7). (Partial immersion of adult frogs in 

 solutions of colloidal acid dyes). 



In all of the following experiments, except Experiment 13 e, 

 the hind legs -and caudal half of the body were suspended in the 

 dye solution. 



a) An adult of R. palustris was suspended for short intervals 

 daily from May 30 to June 1, inclusive, in a 1 : 100 solution of try- 

 pan blue and killed on June 2. The actual length of time the frog 

 was suspended in the dye during a period of three days was one 



