1907.] Wheeler, The Polymorphism of Ants. 63 



is also transmitted, since it must be exercised by the fertile females in 

 establishing their colonies." * 



In other words, Emery supposes that the germ-plasm of the social insects 

 is characterized by a peculiar sensitivity which makes it amenable to the 

 different influences to which it is subjected in the fostering environment of 

 the colony. This view, as I shall endeavor to show in the concluding para- 

 graphs of this article, is worthy of more attention than it has received. It 

 was rejected by Weismann in his Romanes lecture on the ground that typical 

 organs like the wings, ovarian tubules, spermatheca, etc. could not dis- 

 appear from the worker by any ontogenetic, but only by a phylogenetic 

 process, but his argument is based on what is known to occur in other ani- 

 mals and necessarily fails to apply to animals which, like the social Hymen- 

 optera, seem to be unique in presenting the very conditions Emery has 

 been trying to explain. 



Wasmann ^ accepts Weismann's view of the determinants and the function 

 of nutrition as a mere stimulus, but he rejects his view that natural selection 

 alone can account for the adaptive structures and instincts of worker ants. 



Forel in his 'Fournis de la Suisse' (p. 440, 441, nota) accepts the Dar- 

 winian view of the origin of the worker caste by natural selection acting on 

 a primitive differentiation of the female into fertile and sterile forms in the 

 sphere of instinct before definite morphological differentiation sets in. In a 

 recent paper ^ he is inclined to side with Weismann and to lay considerable 

 stress on the effects of natural selection and the struggle for existence in 

 producing variation and polymorphism as opposed to the internal factors. • 



Escherich,* has given a valuable review of the subject of polymorphism 

 among ants, without, however, clearly defining the general issues. His 

 own view is apparently in complete accord with that of Weismann. 



Marchal, as the result of his splendid work on the habits of the social 

 wasps,^ has given the following suggestive discussion of polymorphism along 

 the lines suggested by Spencer and Emery: "At the beginning of the social 

 state the infertility of the first brood of progeny produced by the mother 

 gradually became established. This infertility was the result of the 

 necessarily insufficient nourishment distributed by the queen among her 

 too numerous offspring, and the eggs in the ovaries of the young females 

 could not mature, first, because the reserve substances (adipose tissue) 



1 For a fuller account of Emery's views, see his article ' Le Polymorphisme des Fourmis et 

 laCastration Alimentaire.' Compt. Rend., 3me. Congr. Internat. Zool., Leyde (Sej)!. 189.5), 

 1896, pp. 395-407. 



^ Die ergatogynen Formen, etc., lor. cit., p. 638. 



3 Uetier Polyniorphisinus und Variation bei den Amei.seii. Zool. Jalirb., 8uppl., VII, 1904, 

 pp. 571-586. 



■> Die Ameise. Schilderung ihrer Lebensweise. Braunschweig, 1906, pp. 45-54. 



5 La Reproduction et 1' Evolution des Gugpes Wociales. Arch. Zool. E.\p6r. et G6n., 3. ser., 

 IV, 1896, pp. 1-100, 8 figs. 



