213 
-ments and which fact should be particularly noted), both were pro- 
vided with fresh food to keep the circumstances as equal as possi- 
ble. Five days elapsed between two successive harvests; during all 
the time of the experiment the jars remained in the incubator. 
The result of the first 5 harvests is shown in the table on page 212. 
As the table shows, the average deathrate in the jar without 
slices was about 17°/, higher than in the one with slices, The food 
was renewed twice, viz. on April 12 and 21. In both eases the 
food with slices had already become so crumbly that it had to be 
removed. Uuder ordinary circumstances, the renewal of the food of 
the other vessel (the one without slices) would not have been neces- 
sary. As has been said already, this case occurred repeatedly in all 
series experimented on. At the end of the 5 harvest the larvae 
were sieved and counted to verify all figures. 
Jar A. Experiment III a. without slices) 
Number of larvae the culture was started with... 1000 
on the sieve were left . . . . 642 larvae 
living + dead pupae gathered. . 321 „ 
dead larvae af 4s, 
total 1000 
Jar B. (Experiment III a with slices). 
Number of larvae the culture was started with... 1000 
on the sieve were left . . . . 629 larvae 
living + dead pupae gathered. . 343 „ 
dead larvae 28 5 
total 1000 
The subsequent series of harvests were dealt with as follows. 
The slices of potato were added to those larvae that had never 
enjoyed them, i.e. to the 642 larvae of jar A. The 629 larvae of 
jar B, which had always had slices hitherto, had to do without 
this addition. 
The figures of the harvest of this series are given in the table 
on the following page. 
With the exception of the 1st and the 6'» harvest the mortality 
figure for the jar without slices was considerably higher again in 
each successive harvest. That the lt harvest should be an exception 
to it could not but be expected. The larvae had, indeed, in the former 
harvest, profited from humid surroundings, and the after-effeet of this 
manifested itself in the next harvest in spite of the changed condition. 
The 5°/, lower deathrate in the jar without slices does not therefore 
