THE INTERNAL STRUCTURE OF .1NTS. 



43 



of 20-50 cm., or injected into wounds inflicted with the mandibles. 

 Beyer ( 1890), who has made a comparative study of the development 

 of the poison apparatus in the honey-bee, wasp, Myrmica and Formica, 

 finds that it is smallest in the forms with the largest sting (bee) and 

 largest in forms with only a functionless vestige of this organ. The 

 enlargement and extraordinary convolution of the gland in the Campo- 

 notinae is therefore correlated with a degeneration of the sting as an 

 organ of defence and the development of a novel method of using the 

 poison in conflicts with hostile ants and other animals. 



Apart from a recent paper by Melander and Brues ( 1906), little has 

 been published on the chemical constitution of the poison of ants in 

 general. These authors find appreciable traces of formic acid, as a 



FIG. 21. Poison apparatus of a Dolichoderine and a Myrmicine ant. (Forel.) 

 .-/, Botlinoiiiyrinc.v incridionalis ; B, Myrmica lerinodis. a, Sting; b, sting-groove; 

 <:, sting-sheath ; d, accessory gland ; e, duct of poison vesicle ; f, poison vesicle ; g, 

 bourrelet-like termination of poison glands ; h, poison glands ; i". unpaired, convoluted 

 portion of poison gland; k, film of secretion(?) surrounding bourrelet. 



rule, only in the Camponotinse, that is, in the forms with the pulvinate 

 glands. In this group, as would be expected, the species of Formica 

 head the list with more than twice as much acid relatively to their size 

 as the species of Camponotus. In the Doryline ants (various species 

 of Eciton ) the secretion has a very strong and nauseating, fecal odor 

 like that of the lace-wings (Chrysopa}. Melander and Brues believe 

 this to be due to leucine, and they state that " these ants are totally 

 blind, and migratory in their habits, so that they must depend almost 

 entirely upon a sense of smell to follow one another about. Thus it 



