88 Bulletin American Museum of Natural History. [Vol. XXIII, 



holds them in place with the claws and mandibles, while the other moves 

 the spinning larvffi back and forth within the nest till the rent is repaired 

 with silken tissue. 



3. An interesting case is presented by the honey-ants (Myrmecocystus^ 

 melliger and miexicanus). All the workers of these species, though vari- 

 able in size, are structurally alike. Among the callows, however, and quite 

 independently of their stature, certain individuals take to storing liquid 

 food, as 1 have found in my artificial nests of the latter species, and gradually 

 in the course of a month or six weeks become repletes, or plerergates. Ex- 

 cept for this physiological peculiarity, which gradually takes on a morpho- 

 logical expression, the plerergates and ordinary workers are indistinguish- 

 able. We must assume, therefore, that the desire to store food represents, 

 an instinct specialization peculiar to a portion of the callow workers. There 

 can be no doubt that as our knowledge of the habits of ants progresses many 

 other cases like the foregoing will be brought to light. 



It may be maintained that in these cases physiological states must pre- 

 cede the manifestation of the instincts, and that these states, however inscru- 

 table they may be, are to be conceived as structural differentiations. There 

 is undoubtedly much to justify this point of view. The elaborate sequence 

 of instincts in the queen ant, for example, is accompanied by a series of 

 physiological changes so profound as to be macroscopical. After the loss 

 of her wings, the wing muscles degenerate and the fat-body melts away to. 

 furnish nourishment for the ovaries, wdiich in the old queen become enor- 

 mously distended with eggs as the breeding season approaches. Such 

 changes would seem to be amply sufficient to account for the changing 

 instincts. As I have shown,^ mere artificial dealation at once alters the 

 instincts of the queen, probably through a stimulus analogous to that which 

 leads to the atrophy of a muscle when its nerve is severed, and in the case 

 under consideration leads to the degeneration of the wing-muscles and to 

 changes in the ovaries. 



In the mermithergates and- pseudogynes described in the first part of 

 this paper, the aberrant instincts may be referred to peculiar physiological 

 states. Similarly nutricial castration itself, considered as an instinct, may 

 be said to be the result of the physiological state of hunger. There is indeed 

 every reason to suppose that the worker, both in its ontogenetic and phy- 

 logenetic development, is through and through a hunger-form, inured to 

 protracted fasting. Miss Fielde has shown,^ that the workers of Campono- 

 tus americanus may live nearly nine months without food, which is as long 



1 On the Founding of Colonies, etc., loc. cit., p. 103. 



2 Tenacity of Life in Ants. Biol. Bull., VII, No. 6, Nov. 1904, p-. 300; and ihid.. Tempera- 

 ture in the Development of Ants, loc. cit., p. 366. 



