THE INTERNAL STRUCTURE Ol : ANTS. 55 



Forel ( 1874) first observed that these bodies are largest in worker ants, 

 smaller in the queens and vestigial in the males, and as the worker was 

 supposed to be the most, and the male the least, intelligent, this was 

 regarded as additional evidence in favor of Dujardin's opinion. The 

 condition described by Forel for the ants was affirmed by Brandt (1876) 

 for the social Hymenoptera in general. More recently Kenyon (1896). 

 after an elaborate study of the bee's brain, has reached a similar conclu- 

 sion. He says : "All that 1 am able at present to offer is the evidence from 

 the minute structure and the relationships of the fibers of these bodies. 

 This seems to be of no inconsiderable weight in support of the general 

 idea started by Dujardin. For in connection with what was made 

 known by Flogel and those before him and has since been confirmed 

 and extended by other writers, one is able to see that the cells of the 

 bodies in question are much more specialized in structure and isolated 

 from the general mass of nerve fibers in those insects where it is gener- 

 ally admitted complexity of action or intelligence is greatest." He also 

 cites experiments of Binet ( 1894 ) which tend to show that in insects 

 " when connections between the dorso- and ventro-cerebron are de- 

 stroyed, the phenomena afterwards observed are similar to those seen 

 in a pigeon or mammal when its cerebral hemispheres are removed." 

 In support of Dujardin's hypothesis, Forel has published a series 



FIG. 29. Heads of worker (A), female (6), and male (C}, Formica fusca, drawn 

 under the same magnification, with brain, eyes and ocelli viewed as transparent 

 objects. (Original.) Letters as in Fig. 28. 



of figures of the brain of the worker, female and male of the European 

 Lasius fiilif/inosns, drawn to the same scale (1904). I here introduce 

 a similar series of the American L. brevicornis (Fig. 28). Comparison 

 of these figures shows that the pedunculate bodies do, indeed, vary 

 quite independently of other portions of the brain and in the manner 



