624 



(Zeiss 2 A A), but no trace of a papilla could be found. A drawing of 

 one of the thumbs at this stage and a small piece of its outline under 

 a higher power is given in figs. 2 and 2a. 



During October and November 1912 I examined the remaining 

 thumb and could not detect any growth of papillae, but in January 1913 

 an inspection of the thumb roused my suspicions and on examining it 

 under a lens I noticed to my great surprise the presence of marked pa- 

 pillae all over the thumb pad. The animal was killed at the end of Ja- 

 nuary 1913 and the thumb was examined both under low and high po- 

 wers, and the condition of the papillae is shown in figs. 3 and 3a. It is 

 clear that a very marked new growth of papillae has occurred since the 

 assumption of the perfectly smooth condition shown in figs. 2 and 2 a. 

 The animal was dissected in order to make sure that no testicular tissue 



/) 



1a. <3* 



Fig. 1. Thumb of Male on Dec. lo* 1 1911, at time of castration, a. More highly 



magnified view of some of the papillae of above. 

 Fig. 2. Thumb of same male in September 1912. a. More highly magnified view of 



outline at this time, showing entire absence of papillae. 



Fig. 3. Thumb of same male in January 1913, showing re-growth of papillae, a. More 



highly magnified view of the papillae at this time. 



had been left behind, but the dissection revealed an entire absence of 

 the testes which had been completely removed. The frog weighed at 

 death about 12 grammes, having thus lost about 3 grammes in weight. 



We see, therefore, that a male frog completely castrated in De- 

 cember 1911, after acquiring perfectly smooth thumbs without a trace 

 of papillae on them in the summer and autumn of 1912, grew papillae 

 again in January 1913, without any experimental treatment at all. 



Now the validity of Profs. Nussbaum's and Meisenheim er 's 



