382 the president's address. 



one of which is published in your Proceedings. Newton did good 

 service by his English rendering of Flogel's nomenclature. 



The most important contribution to our knowledge on this sub- 

 ject which has been published in the English language is 

 Packard's " Monograph on the Brain of the Rocky Mountain 

 Locust," in the United States Entomological Commissions' Report 

 for 1880, and by far the most detailed and recent work is that of 

 Dr. H. Viallanes on the brains of the wasp and cricket in the 

 " Annals de Sciences Naturelles " for 1887 and 1888. 



It is now usual to speak of the cephalic nerve centres of insects 

 as the brain, but all those who have written upon the subject have 

 retained the old view that this structure consists of several ganglia 

 corresponding to a similar segmentation of the head. Thus we 

 find discussions as to the number and relations of the prestomal 

 ganglia and segments. 



The theory of segmentation was formerly applied to the verte- 

 brate skull, and originated in the brains of Oken and Goethe. 

 Professor Huxley, in his lectures on the vertebrate skull published 

 in London in 1864, disposed for ever, I believe, of these views, 

 and showed clearly that the skull is developed from parts which do 

 not undergo segmentation. My own researches in the embryology 

 of insects have sufficiently shown me that the brain and head cap- 

 sule of insects are also developed from structures, the procephalic 

 lobes of Huxley, which undergo no segmentation. I am indeed con- 

 vinced that there are no prestomal segments in insects. 



Viewed in relation to development, the brain in insects consists 

 of a central ventricle and two hemispheres, which are themselves 

 hollow. The central ventricle contains a transverse and longitudi- 

 nal commissure, the corpus centrale, and is connected by its posterior 

 wall with the median eyes or ocelli. There is thus a close correspon- 

 dence between the brains of vertebrates and those of insects. The 

 so-called antennal lobes correspond to the olfactory bulbs, the 

 central ventricle to the third ventricle, and the ocelli to the pineal 

 gland or pineal eye where the latter is developed. The hemispheres 

 are cerebral lobes, and the pedunculated bodies are merely isolated 

 convolutions of the surface. My unpublished work on this subject 

 will occupy some thirty closely-printed pages at least. 



The last subject in connection with the anatomy of insects to 

 which I shall draw your attention is perhaps the most interesting 

 and important of all — the history of the development of the indi- 



