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still contain plenty after soaking, but that all the sugar, or most 
of it, would disappear. It may be concluded also that immunity 
from attack would not be due to such reduction in starch-content 
as takes place, but that the removal of sugar may perhaps be the 
change which confers immunity. 
The following experiment was carried out with a view to testing 
the value of these deductions : — 
Three boring beetles (Vinoderus minutus), were placed in a 
corked glass-tube with three strips of bamboo. The pieces of bam- 
A second untreated strip was placed in the tube with the 
beetles; this also was attacked, a new brood of beetles was pro- 
duced, and eventually the material of both untreated pieces 
became nearly exhausted, when a slight further attack of the 
treated piece took place. 
urther experiments were prevented from being carried out 
by the death of the beetles. 
The powder produced by the beetles in boring an untreated 
piece of bamboo, in which starch and sugar were abundant 
found to contain, besides the woody fibre, plenty of starch, but 
only a very small amount of sugar. Practically all this powder 
had no doubt passed through the alimentary canal of the insects, 
but some fragments which had not been ingested may have been 
bong. and possibly the sugar detected may have belonged to 
ese. 
Further Experiments. 
Four more beetles having been obtained, they were put into 
two jars with treated and untreated pieces of bamboo, three 
beetles in one 
amount of glucose. In both eases also a small boring had been 
first begun in a treated piece from the same stem, that in jar B 
Pod a lucose had been restored to the 
It is possible, however, that an unsuitable 
