( ci ) 
with its gem-plasm. The interest and importance of these 
results is manifest, and it is well to remind ourselves once 
more that they all emerge from the careful study of an 
insect. 
Experiment 2.—Males and females of L. decemlineata were 
subjected to hot dry conditions, and afterwards to normal 
surroundings. During each period they deposited eggs. 
From the eggs deposited in the second peidod, that of normal 
conditions, pure decemlineata were bred for ten generations. 
But from the eggs of the first period came many aberrant 
forms, together with a certain number of apparently typical 
decemlineata. These latter were reared side by side with the 
decemlineata of the second period, which, as we have seen, 
behaved in a pei’fectly normal manner throughout. But the 
decemlineata of the first period, after giving rise to a genera¬ 
tion of apparently quite normal forms, suddenly developed into 
a race with an annual cycle of five generations instead of the 
normal two, and continued to exhibit the same abnormality 
up to the fourteenth generation, when the experiment ceased. 
Here we have a physiological instead of a structural pecu¬ 
liarity imposed upon the germ-plasm by artificial means, and 
giving rise to a permanent race. It should be mentioned 
that, in the words of Tower, “ none of the beetles of the 
lineata group, to which this beetle belongs, have more than 
two, or rarely three, generations per year, and there are none 
known in the genus that have over three.” Another point 
that emei’ges is that the application of the stimulus need not 
always be immediately followed by the obvious response. In 
the present experiment one whole generation elapsed before 
the race began to show the effect of the abnormal treatment 
to which its progenitors had been subjected. 
Experiment 3. — In another experiment with the same 
species the conditions were varied by using heat in combina¬ 
tion with moisture. In other respects the procedure was the 
same. From the eggs of tlie second period eight successive 
generations were reared, giving nothing but pure decemlineata. 
From those of the first period, that of abnormal conditions, 
came a large number of unmodified decemlineata and a certain 
number of the form melanicum. Both of these forms bred 
