110 
Psyche 
[December 
laid, and that these eggs become queens or workers respec- 
tively according to the nature of at least one environmental 
factor acting upon them after being laid. The present 
experiment goes even farther than this, for in it the deter- 
mination of queens and workers was effected at a compara- 
tively advanced stage in larval growth, indicating that final 
determination may be considerably postponed. Exactly what 
environmental factors are involved is not evident. Quantity 
of food is one factor, from the nature of the experiment; 
but that is not all, for attempts to produce queens from L. 
curvispinosus larvse during the summer by overfeeding met 
with no success. Larvse on emergence from hibernation, 
therefore, differ from larvse during the rest of the year in 
being, somehow, peculiarly susceptible to a “gynegenic” in- 
fluence of quantity of food. This influence may be direct or 
may be transmitted to the larvse secondarily through the 
workers. Perhaps it is the action of factors arising from 
various seasonal changes which produces this different re- 
sponsiveness on the part of overwintered larvse. 
Now we can trace a possible pattern of events. As Winter 
approaches, there remains in the nest a variable number 
of larvse of varying size whose growth has been brought to a 
standstill by the decline in food and increase in cold weather, 
possibly other factors. These larvse emerge in the Spring 
somewhat reduced in size, but with their physiology so al- 
tered that under the influence of an abundant available food 
supply they can start development toward the queen form. 
All the larvse are not the same in their susceptibility, how- 
ever, so that when the food supply is small, only the most 
susceptible are affected; and there may be some, perhaps 
small or feeble larvse, which are not affected at all. The 
larger the food supply, the more less susceptible larvse are 
affected. This period of susceptibility lasts only a short 
time (indicated by the fact that the pupation curve of the 
queens in colony B is quite short and is simultaneous with 
the curve for A), after which the larvse become resistant to 
the gynegenic action of food and become workers no matter 
how much food is offered them. While the queen larvse 
are developing, the largest proportion of the available food 
goes to them, the rest of the larvse taking comparatively 
little (indicated by the separation of queen and worker pu- 
