ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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trated by almost all Poneridie, many Myrmicidse, several Dolichoderidm 
and Camponotidfe. In most Poneridm, the workers differ but slightly 
from the queens, and in some species ( Odontomachus haematodes and 
chelifer , Pachycondyla villosa) there are transitional forms between 
workers and queens. 
II. Ants with large and small workers (Di- and Polymorphism of 
workers). Here (a) the extreme forms may be connected by interme- 
diate grades, as in many Myrmicidee, most Camponotidae, Azteca among 
the Dolichoderidae ; or (6) the large and the small forms are distinct 
castes without intermediate forms : — the soldiers and workers of Pheidole , 
Acantliomyrmex , some species of Camponotus, and among these most species 
of the sub-genus Colobopsis. Here it may be noted that it seems a 
general fact true of both ants and termites that the reduction of the 
reproductive organs is associated with a stronger development of the 
head. 
III. Ants with only small workers, which are very different from the 
females. This state is supposed to have arisen from the dimorphic con- 
dition, through the disappearance of the large workers. To this grade 
belong only a few genera, such as Solenopsis, Garebara, and perhaps 
Monomorium. In some there are hints of dimorphism. 
IV. Ants with only one kind of worker, much smaller than the 
females, but differing from III. inasmuch as they seem not to have 
sprung from dimorphic forms, but to owe their relative inferiority in 
size to an increase in the size of the females. There are often slight 
differences in the size of the workers. This condition seems to have 
arisen “ polyphyletically,” and occurs in species of Iridomyrmex, Dory - 
myrmex, in many species of Lasius, and in most species of Crematogaster. 
The small males give some hint of the original size of the females, 
which is retained in some species. 
Y. Lastly, there is a disappearance of the worker-caste, in consequence 
of parasitism. This is completely illustrated by Anergates and probably 
by Epoecus , and is hinted at in Strongylognathus. In Torino gnathus there 
seem to be no normal queens, but only parthogenetic workers. 
The phylogeny of ants is unfortunately unknown ; Emery presup- 
poses merely a primitive society such as is found in many Poneridse and 
Myrmicidse. He supposes that in such a society the art of rearing 
sterile workers had been discovered, and that the origin of workers 
depends on a special capacity of the germ-plasm to react to a certain 
nutrition which hastens the development of some parts and retards 
others, of jaws and brain, as against wings and gonads. Besides quali- 
tative differences in nutrition there are also quantitative differences, 
probably older, in consequence of which the workers remain smaller 
than the queens. Presupposing an instinct for rearing workers, Emery 
believes that their origin depends mainly on the quality of the food, 
their differentiation more on the quantity. His general idea is that the 
qualities which distinguish the workers from the sexual animals are not 
innate or blastogenic, but acquired or somatogenic. They are not 
transmitted as such, but in the form of a capacity which the germ- 
plasm has to react to given conditions. Similarly, myopia is somato- 
genetic, but has a blastogenic foundation. 
