185 



The following Table shows the day on which each larva began to 

 spin ; the day on which the perfect insect Escaped from the pupa ; 

 and hence the number of days occupied by the metamorphosis. 



From this it is seen that the mean period occupied by the meta- 

 morphosis in the darkened cell was eighteen days fifteen hours, and 

 in the light cell seventeen days sixteen hours. 



The longest and shortest periods in the darkened cell twenty-two 

 days and seventeen days, in the light cell nineteen days and seven- 

 teen days. 



June 9th. On selection of sixteen of the largest larvee from the 

 inhabitants of each cell, it was noted that, when sixteen were selected 

 from the darkened cell and several of similar size removed, only 

 four could be found as large in the white cell, the remaining twelve 

 selected were therefore of a rather smaller size. This difference in 

 the two cells became less obvious afterwards, but, throughout the 

 experiments, there was a slight difference of size in favour of the 

 darkened cell. 



With these exceptions, no difference could be detected between the 

 results obtained in the cell from which light was completely excluded 

 and in that exposed to its full influence. 



The larvse, the silk produced, and the moths from the two cells, 



