215 
form an exception, but on the contrary, confirms the rule that the 
addition of slices caused a strong regression of the death rate of the pupae. 
The exception of the 6" harvest had been brought about by the 
circumstance that in consequence of the excessive humidity in the 
jar with slices, the food had clotted and grown quite mouldy. 
The wall of the jar was covered with big drops of water. 
The 7 dead pupae gathered had not been gnawed at, indeed, but 
were black. Here the too much of a good thing, had apparently 
produced a reverse effect. The food of the jar under discussion had 
to be renewed for that reason, and this was done in both vessels, 
again for the sake of the uniformity of circumstances. 
Notwithstanding these two exceptions the average mortality of the 
9 harvests had fallen by 24°/, for the jar with slices after all. 
At the close of the 9th harvest of the above trial series IIId, the 
larvae were sieved and counted to verify the figures obtained, with 
the following result: 
Jar A. (Experiment IIb without slices). 
Number of larvae this series was started with. . . 629 
On the sieve were left . . . . . 398 larvae 
Living + dead pupae ee en € 20D 
Dead larvae... RT NE 26 
Total 629 
Jar B. (Experiment IIIb with shces). 
Number of larvae this series was started with. . . 642 
On the sieve were left . . . . . 418 larvae 
Living + dead pupae pees ee 209 
Dead larvae .- . . Lenn 22 
Total 1.2. el eae 
More individuals accounted for than there were at the outset i 
The verification of jar B shows an excess of 7 individuals. 
How the error has arisen, is not known. As a rule such a veri- 
fication shows a deficit, as the remains of a number of individuals 
are not found back. The mistake, however, if it has been made by 
inaccurate counting, cannot raise the deathrate, but rather lowers it, 
so that one need not care about it any further. For the 3rd harvest 
series the slice-food was again reversed. 
The 418 slice-larvae of Jar B no longer got any slices; the 398 
of jar A, which had not had any slices in the 2rd harvest series, 
were provided with them now. The result of this 3rd series, with 
a summary of the three series together is given on page 216 
