1953] 
Wilson — Caste Deter minatioyi 
19 
material in the egg determines caste by predetermining 
exactly the size reached by a larva at various stages of its 
development. Such a proposition would be wrong, of course, 
since it is a commonly observed fact that the growth of 
larvae can be changed greatly by simply varying the amount 
and kind of food supplied the colony. It appears to the 
present writer that Flanders’ explanation has a good 
chance of holding only under certain conditions of com- 
plete dimorphism. It is not impossible that in extreme 
cases the critical developmental time mentioned above can 
be pushed back in ontogeny all the way through the larval 
period and to the embryonic period within the egg, so that 
the imaginal disc potentials are already fixed at the time of 
eclosion from the egg. On the other hand, ovisorption 
might exercise a subsidiary infiuence in caste determina- 
tion by statistically affecting the chances of a larva attain- 
ing the important size levels during its growth; existing 
data on larval development are not complete enough to 
evaluate this particular aspect. Whether ovisorption ever 
actually plays these two roles remains to be seen, but at 
the present time this outstanding fact must be accepted: 
there is no direct evidence upon which to base such an 
assumption. 
Literature Cited 
Bhattacharya, G. C. 
1943. Reproduction and caste determination in aggressive red-ants 
Oecophylla smaragdina Fab. Bose -Research Institute, Calcutta. 
Brian, M. V. 
1951. Caste determination in a myrmicine ant. Experientia, 7: 1-4. 
Eidmann, H. 
1931. Die Koloniegriindung von Lasius flavus F. nebst weiteren 
Untersuchungen tiber die Koloniegriindung der Ameisen. Biol. 
Zentralbl., 51: 657-677. 
Flanders, S. E. 
1945. Is caste determination in ants a function of the rate of egg 
deposition? Science, 101: 245-246. 
1952. Ovisorption as the mechanism causing worker development 
in ants. Jour. Econ. Ent., 45: 37-39. 
Goetsch, W. 
1937. Die Entstehung der “Soldaten” im Ameisenstaat. Naturwis- 
sensch., hrsg. A. Berliner, 25: 803-808. 
