1908] The Polymorphism of Ants 49 



transmitted as such, but in the form of a pecuHarity of the germ- 

 plasm that enables this substance to take different developmental 

 paths during the ontogeny. Such a peculiarity of the germ may 

 be compared with the hereditary predisposition to certain diseases, 

 which like hereditary myopia develop only under certain condi- 

 tions. The eye of the congenitally myopic individual is blasto- 

 genetically predisposed to short-sightedness, but only becomes 

 short-sighted when the accommodation apparatus has been over- 

 taxed by continual exertion. Myopia arises, like the peculi- 

 arities of the worker ants, as a somatic affection on a blastogenic 

 foundation. 



"With this assumption the problem of the development of 

 workers seems to me to become more intelligible and to be brought 

 a step nearer its solution. The peculiarities of the Hymenopteron 

 workers are laid down in every female egg; those of the termite 

 workers in every egg of either sex, but they can only manifest 

 themselves in the presence of specific vital conditions. In the 

 phylogeny of the various species of ants the worker peculiarities 

 are not transmitted but merely the faculty of all fertilized eggs 

 to be reared as a single or as several kinds of workers. The pecu- 

 liar instinct of rearing workers is also transmitted since it must be 

 exercised by the fertile females in establishing their colonies." 



The views above cited show very clearly that authors have 

 been impressed by very different aspects of the complicated phe- 

 nomena of polymorphism, and that each has emphasized the 

 aspect which seemed the most promising from the standpoint of 

 the general evolutionary theory he happened to be defending. 

 Escherich (1906) has recently called attention to two very differ- 

 ent ways of envisaging the problem; one of these is physiological 

 and ontogenetic, the other ethological and phylogenetic. As these 

 furnish convenient headings under which to continue the discus- 

 sion of the subject, I shall adopt them, and conclude with a third, 

 the psychological aspect, which is certainly of sufficient impor- 

 tance to deserve consideration. 



While the ontogeny of nearly all animals is a repetition or re- 

 production of the ontogeny of the parent, this is usually not the 

 case in the social Hymenoptera, since the majority of their fer- 

 tilized eggs do not give rise to queens but to more or less aberrant 

 organisms, the workers. i\nd as these do not, as a rule, repro- 

 duce, the whole phenomenon is calculated to arouse the interest 

 of both the physiologist and the embryologist. The former, con- 



