Mr. P. A. Buxton on Protocerebrum of Micropteryx. 113 



that some apology should be made, because I do not at 

 any rate describe the whole brain : it is owang to the war 

 and pressure of other work that there is no likelihood of my 

 being able to carry my investigations further. This paper 

 is however complete in itself, and is not of the nature of a 

 preliminary note. From the point of view of comparative 

 anatomy, the Protocerebrum, vnth which alone this paper 

 deals, is by far the most important part of the insect brain, 

 not only on accomit of its complicated structure, but also 

 because of certain questions relating to the homologies of 

 some of its parts. Such questions of homology do not at 

 present arise in connection with the Deuterocerebrum or 

 Tritocerebrum, or ventral brain. My hope that my inves- 

 tigations would throw light on the systematic position of 

 Microjjteryx will not be fulfilled until we can compare the 

 brain of this insect with, a number of other Lepidopterous 

 and Trichopterous brains, after they have been fully and 

 properly investigated. 



I have made some attempt to render this paper useful 

 also as an introduction to the study of the brain of insects ; 

 this I think is justified, because it is the first paper on the 

 subject published in Great Britain since 1878 (Newton), 

 and I know by bitter experience how exceedingly difficult 

 it is to obtain a clear knowledge of the subject from a 

 variety of papers written by many men in many languages 

 at different dates. My task has been rendered difficult 

 by the small size of Micropteryx, which is, I believe, the 

 smallest insect of which the brain has been investigated 

 in any detail. 



I take this opportunity of acknowledging how much I am 

 indebted to many friends in the University's Zoologicaf 

 Laboratory at Cambridge, particularly to Mr. F. Balfour 

 Brownie for constant criticism and much good advice, and 

 for reading through the whole paper before it was published ; 

 also to Mr. L. A. Borradaile for helping me with the theory 

 of the segmentation of the head of the Arthropoda ; also 

 to Dr. D. Keilin of the University of Paris, and of the 

 Quick Laboratory and Magdalene College, Cambridge, for 

 putting at my disposal his deep knowledge of fixing and 

 staining. Canon W. Brocas Waters gave me a room to 

 work in, while I was stationed in Bury St. Edmunds on 

 military duties. 



I must also acknowledge my indebtedness to Dr. K. F. 

 Kuhnle of Stuttgart for his paper on the brain of the 



TRANS. ENT. SOC. LOND. 1917. — PART I. (nOV.) I 



