148 EDUARD UHLENHUTH 
under these conditions the quantity of food spontaneously taken 
is really a function of growth. On the contrary it appears very 
probable that the reduced amount of food taken must be at- 
tributed to disturbances caused in the swallowing apparatus by 
the convulsions. In such a ease the animals would be in a 
condition of starvation and in contradiction to the idea of the 
experiment the rate of growth would be the function of the food 
quantities introduced into the organism. I thought to be able 
to overcome this obstacle in another group of experiments, in 
which I proceeded from the fact that when food is present in 
sufficient quantities equal amounts of food produce an equal 
rate of growth. 
In a group consisting of 4 series (O 1916) for which larvae of 
A. opacum were used, the food was given in small fragments 
at the point of the forceps in all the series; an attempt was made 
to make all the pieces of approximately the same size on the same 
day of feeding. The number of pieces given to each individual 
animal was noted, and on each feeding day approximately (for 
the week) the same number of pieces was given, so that all the 
animals of these 4 series received approximately the same 
number of pieces, the series comprising one thymus and one worm 
group at an average temperature of 22.6°C., and one thymus 
and one worm group at about 14.8°C. An effort was hereby 
made to distribute a quantitatively equal amount of food among 
the 4 series; but it must be remarked that this can only be 
roughly attempted and cannot be exactly carried out. As it 
ean never be known beforehand how much food the animals 
may need on a given day in order to be satisfied, it would also 
be quite impossible to weigh the food. But even if this were 
possible, the distribution of equal quantities according to weight 
would not lead to the distribution of equal nutritive quantities 
as a given volume of thymus contains a larger quantity of sub- 
stances available for metabolism than does the same quantity 
of fragments of earth-worms, as has been shown in the first 
experimental group. Although this method is not exact, it 
has at least furnished an approximate idea as to how important 
it is to control the quantity of food in such experiments. 
