462 
GEOFFREY SMITH AND EDGAR SCHUSTER. 
observations, we hold them to be insufficient, because there is 
no real evidence produced, apart from the mere inspection of 
the thumb at different times during the experiment, to show 
that small papillae of the size of those shown in Nussbaum’s 
figures, depicting the condition at the end of the experiment, 
were not present at the beginning of the experiment as well. 
We hold that the mere inspection of the thumb and a state- 
ment of the impression of the observer as to its state of 
papillation is not sufficient to prove a quantitative alteration 
in the degree of papillation such as is claimed in the 
experiments before us. The frogs were castrated in May and 
•June, and it is stated that the pads were smooth. In our 
Table for normal frogs during May and June, half of the 
individuals had thumb-pads which on mere inspection might 
be described as smooth, but which on examination under the 
microscope revealed the presence of definite papillae. 
If such frogs were castrated there is nothing to show that 
the papillae would disappear, as our evidence on castrated 
frogs goes to show that when frogs are castrated the thumb- 
pads remain in statu quo as regards the development of 
papillae. Then on examining them in the following autumn 
a careful examination of the whole thumb, or of sections, 
would reveal the presence of papillae, as in the case of 
Nussbaum’s frogs, which were treated with testis injection 
and implantations. 
hfow let us turn to Meisenheimer’s more recent observa- 
tions. This author claims to have confirmed Nussbaunds 
results, but he has added to them in a remarkable manner, 
because he believes that he has induced the development of 
papillae on the thumb-pad, not only by the implantation of 
testis-pieces, but also by the implantation of pieces of 
ovary. This truly amazing result is based on a number of 
experiments which appear to us quite unconvincing. Meisen- 
heimer castrated his frogs in autumn or winter (September 
or January), and he states that the result of the opera- 
tion “ war eine sehr prompte, sie bestand in Uollen 
Ubereinstimmung mit Nussbaunds Ergebnissen in einer 
