A quantitative Study of Variation, Natural and Induced, etc. 187 
heat, moisture etc. Pedigreed cultures have been used and important 
experiments repeated several times so that the data collected are of 
great value. A few quotations will serve to give some idea of the 
work and the success attained measured in terms of new forms pro- 
duced. “The use of moisture and temperature in unusual degrees of 
intensity has given rise to a number of modified forms and characters. 
From a normal form of L. undecimlineata a race was derived which 
resembles Jocoby’s L. angustovittata and it breeds true to the type. 
(Illustrated) The eggs that had been subjected to the changed 
environment, fertilized with normal male germs produced mutants 
which breed true without subsequent segregation. In some cases the 
male germinal material was worked upon and in others the female 
substance. In some cases the change was shown in the first generation, 
in others successive generations were required. So long as there is 
no segregation or reversion after the mutation is produced the time 
required to fix the change is not of prime importance. Not all germ 
cells are modified. This may indicate differences between the eggs 
in their capacity for modification, or that only certain eggs were in 
the proper stage for modification at the time of the application of 
the experimental conditions. The results are sometimes modifications 
all in one direction, at other times they are in many directions, two, 
three, or more different forms arising from the same experiment. 
Some characters have no intergrades, others have intergrades and 
there is no place where one can draw a line and say that on one 
side all are discontinuous variations and on the other they are con- 
tinuous‘. 
In Blaringham’s experiments to produce mutations by artificial 
means, he subjected indian corn (Zea Mays) to various mutilations. 
(1) The stalk was cut transversely near the ground through a greater 
or lesser part of its body. (2) The stalk was split longitudinally 
from near the ground upwards for varying distances. (3) The principle 
stalk was twisted about its own axis to varying degrees. (4) In refer- 
ence to the ears alone the developing ear was twisted about its axis 
to varying degrees. Many striking variations were produced some of 
which breed true without regression or segregation. Four new forms 
have been produced which reproduce true to type. These differ in 
color of grain, character of growth, etc. 
In the experiments briefly reviewed and others that might be 
cited we see that mutations have been produced by artificial means; 
striking variations from the parental form which breed true and become 
