138 EDUARD UHLENHUTH 
obtained in both series are the expression of the quality of the © 
food. 
The development of the legs and toes was carefully noted, and 
the development of these organs was seen to occupy a period of 
from 6 to 9 weeks. As the thymus feeding began as early as the 
second week, the development of the legs took place under the 
influence of thymus feeding during 4 to 7 weeks. According to 
’ Gudernatsch and Romeis this length of time sufficed in the case 
of tadpoles to produce the retarding effect upon development of 
the thymus; but in the case of the Salamander larvae absolutely 
no retardation could be noted as a consequence of the thymus 
feeding. Indeed, in those series which as a result of the simul- 
taneous effect of a lowered temperature necessitated a longer 
period of time in order to attain complete development, a change 
in the contrary direction could even be noted in the latest stages, 
the thymus animals attaining complete development of their 
limbs more quickly than the worm-fed animals. 
Thus it can hardly be argued in this connection that feeding 
had not lasted long enough to produce a result, in view of the 
fact that in the latest stages of development of the legs when the 
feeding had lasted a longer period than in the first stage, the 
opposite result was obtained. ‘This result then indicates that a 
distinct difference exists between the Anura and Urodela with 
respect to the effect of thymus-feeding upon development. 
The development of the legs in such animals to which instead 
of equal quantities of food as much food was given as each animal 
was able to take, was not studied in sufficient detail. In one 
group of experiments (P 1719) which consisted of A. punctatum 
larvae, development of the legs was recorded during 14 days 
after the beginning of the feeding; in this group the relation be- 
tween the thymus-fed animals and the controls was the same as 
in the above experiments on A. opacum. 
The differences between the Anura and Urodela become 
even more accentuated as development proceeds. But a 
careful distinction must be made between animals fed on 
equal quantities and those which obtain as much food as they 
will take. 
