146 EDUARD UHLENHUTH 
2. GROWTH 
In one series of experiments (P 1917) for which purpose 
larvae of A. punctatum which had hatched on the same day and 
were the offspring of the same mother were employed, it was 
assumed that where there is an unlimited supply of food, the 
amount spontaneously taken up by each animal is a function of 
growth, and that growth is not a function of the food quantity. 
For that reason in these experiments which were carried out at 
an average temperature of about 22°C., the animals were allowed 
as much food as they felt inclined to take. 
The group consisted of three series. The animals of the first 
series were given small equal-sized fragments of thymus with a 
pair of forceps, until each animal was satisfied. They took the 
pieces easily and owing to the softness of the material had no 
difficulty in swallowing them. The second series received frag- 
ments of earth-worms. Owing to the hardness of this food, 
however, the animals found great difficulty in swallowing it, 
and it took several minutes, or even hours for each piece to be 
swallowed. As they were fed only once a day, these worm ani- 
mals remained hungry and consequently were soon backward 
in growth, as compared with the thymus-fed animals. The 
latter finding coincided with the observations made in the case 
of the Anura; i.e., that the thymus stimulates growth; but it 
failed to prove a specific influence of thymus, for the reason that 
the animals which were fed in a normal manner were found to be 
starving. In a third series the animals were fed with small 
worms (Enchytraeus), which were at first given in small pieces; 
these worms were thrown into the containers in such large quan- 
tities that the animals never lacked food. Besides this, each 
animal was fed on pieces of earthworms which the fast-growing 
animals soon took readily and in large quantities. The individ- 
uals of this series grew faster from the very outset than did the 
thymus animals. As the latter did not develop tetany until the 
5th week and were in a completely normal condition until the 
end of the 4th week, we may look upon the result attained up 
to that time as the pure effect of nutrition. The salamander 
