iQoS] The Polymorphism of Ants 53 



because the semipupa, after the detachment of the parasite, seems 

 to undergo a kind of regeneration and produces a small but har- 

 monious whole out of the depleted formative substances at its 

 disposal. What is certainly a female or soldier semipupa takes 

 on worker characters while the worker semipupa may be said to 

 become infra-ergatoid as the result of the sudden loss of the for- 

 mative substances. These observations indicate that the 

 normal worker traits may be the result of starvation or withhold- 

 ing of food rather than of the administration of a particular diet. 



6. The pseudogynes of Formica admit of a similar interpre- 

 tation if it be true, as I am inclined to believe, that they 

 arise from starved female larvse. Here, too, the organism 

 undergoes a kind of regeneration or regulation and assumes the 

 worker aspect owing to a dearth of sufficient formative substances 

 with which to complete the development as originally planned. 



7. In the preceding cases the ants take on peculiar structural 

 modifications as the result of tolerating parasites that bring about 

 unusual perturbations in the trophic status of the colony. When 

 ants themselves become parasitic on other ants a similar perturba- 

 tion ensues, but in these cases the morphological effects are con- 

 lined to the parasitic species and do not extend to their hosts. This 

 must be attributed to the fact that the parasites live in afflu- 

 ence and are no longer required to take part in the arduous and 

 exacting labors of the colony. Under such circumstances the 

 inhibitory effects of nutricial castration* on the development of the 

 ovaries of the workers are removed and there is a tendency for 

 this caste to be replaced by egg-laying gynascoid individuals or 

 by ergatogynes, or for it to disappear completely. These effects 

 are clearly visible in nearly all parasitic ants. In the European 

 Harpegoxenus sublasvis, for example, the only known females in 



* Nutricial castration (from nutrix, a nurse) as understood by Marchal, must 

 be distinguished from alimentary castration (Emery, Le Polymorphisme, 

 etc.), although both are responsible for the infertility of the worker. 

 Through alimentary casl ration the development of the reproductive organs is 

 inhibited in the larva and pupa, and this inhibition is maintained in the adult 

 by the strong nursing instincts which prevent the workers from aiJjjropriating 

 much of the food supply of the colony to their individual use. In manj' of the 

 higher animals also (birds, mammals) reproduction is inhil)ited by the exercise 

 of the nutricial function. A third method of inhibiting or destroying the repro- 

 ductive function is known to occur in the "parasitic castration" of certain bees 

 and wasps (Andrena, Polistes) by Strepsiptera (Stylops, Xenos, etc.) See 

 Perez, Des Effets du Parasitisme des Stylops sur les Apiaires du Genre Andrena. 

 Actes Soc. Linn. Bordeau, 1886, 40 pp. 2 pll. Westwood has also described a 

 Strepsipteron (Myrmecola.x nietneri) which in all probability produces this form 

 of castration in certain Formicidae. .**.. ._ .v «.i 1 



