PSYCHE 
VOL. XLVII DECEMBER, 1940 No. 4 
AN EXPERIMENTAL STUDY ON CASTE 
DETERMINATION IN ANTS 
By Laurence G. Wesson, Jr. 
Boston, Mass. 
There are two theories concerning the method of determi- 
nation of the castes of the female sex in ants. The blasto- 
genic theory maintains that the caste of the individual 
worker or queen is determined in the egg. The trophogenic 
theory maintains that the castes are determined by influences 
upon the egg or resulting larvae after the egg has been laid. 
Between these two theories lies an ill-defined zone in which 
on the one hand environmental influences may be presumed 
to be transmitted through the reproductive female to the 
egg to alter the character of the nutritive material laid down 
for the larvae, or even to alter the genetic pattern. On the 
other hand, it is possible that an inborn tendency to become 
one caste or the other may be only partial, to be altered 
under environmental stress. Definite proof of the blasto- 
genic theory would appear to be a difficult task, and would 
probably require careful genetic and chromosomal studies. 
Certain proof of the trophogenic theory, on the contrary, 
appears much simpler and would consist in the demonstra- 
tion that any arbitrarily chosen female egg can be caused 
at will to develop into either queen or worker through 
control of environmental factors. It is important to note 
here that failure to prove the trophogenic theory does not 
disprove it, for some potent environmental factor may still 
be uncontrolled. 
