116 Prof. E. W. MacBride and Miss A. Jackson. 



The result of this experiment was to show that on the whole fewer browns 

 were produced by insects subjected to diminished light than by those exposed 

 to intense light. To give examples : Of 384 eggs, the progeny of one 

 female, 192 were subjected to bright light and 192 to diffuse light. Of the 

 first lot 55 were reared, including 52 greens and 3 browns : of the second 

 lot 64 were reared, viz., 63 greens and 1 brown. In another case 222 eggs, 

 the progeny of one female, were taken, of these 111 were exposed to bright 

 light and 111 to diffused light. Of the first lot 75 were reared, 72 green and 

 3 brown — of the second lot 87 were raised, all green. 



An attempt was then made to rear a certain number of insects in 

 complete darkness, making use of an extremely ingenious piece of apparatus 

 devised for us by Prof. Lefroy. This consisted of a light-tight box of stout 

 deal divided into an inner and an outer compartment, the whole being 

 painted black. The two compartments communicated with one another by 

 means of a zinc shutter over which was a weighted black curtain. The 

 outer compartment was closed by a wooden frame over which a black 

 curtain was stretched. The frame worked on a hinge and could be raised. 

 In the curtain there were a pair of holes to which black sleeves were 

 attached. These sleeves admitted the arms of an operator, round whose 

 wrists they were tightly secured by elastic. The just-hatched insects were 

 placed on a privet plant in the inner compartment which was watered 

 through an external funnel communicating with the interior by a rubber 

 tube controlled by a tap placed internally. When it was necessary to 

 change the plant the outer compartment was opened and the new plant 

 was placed therein. Then, the outer curtain being down, the arms of the 

 operator were introduced through the sleeves and the wooden frame raised. 

 Then the zinc shutter of the inner compartment was raised and the 

 insects were shaken off the old plant, which was then brought into the outer 

 compartment and replaced by the new one and the zinc shutter closed. 

 When bv feeling it was determined that the insects had become adult the 

 case was opened. 



Three such cases were made. In the first 50 insects were placed 

 immediately after hatching, of which only four survived, and of these one 

 was green and three brown. In the second 50 insects were also placed, but 

 this case was opened from time to time for a minute or two to inspect the 

 insects. Eight insects became adult, and all were green. In the thir*d case 

 an equal number of insects were placed, these were fed on germinating 

 beans, which, growing in the dark, produced only yellowish leaves devoid of 

 chlorophyll. Only one insect survived, and it was vividly green, as if it had 

 been produced under normal conditions. From these experiments it is to be 



