158 E. T. NEWTON ON PREPARING A MODEL OF AN INSECT'S BRAIN. 



those marked (a), (m), (st), we shall obtain models of the mushroom- 

 bodies, with their stems, &c. In this manner the dissected portions 

 of this side of the brain were joined together, and, after some little 

 trouble in adjustment, one was enabled to make the parts fit 

 together in their relative places. We have now, therefore, upon the 

 left side, a model which may, so to speak, be cut up in slices, to 

 show the microscopic appearance of the sections (Fig. 4), and on 

 the right side, a model of the more important internal structures, 

 which may, as it were, be dissected out before a class of students 

 (Fig. 5). 



I was in hopes that, before reading this paper, I should have been 

 able to coustruct a similar model of the Brain of a Bee, in order to 

 verify the descriptions of Dujardin, Dietl, and others, who have 

 worked at this insect, but have not yet had the opportunity. This, I 

 may say, however, that an examination of this model goes far to 

 prove the correctness of their descriptions, for we see here a mass 

 of nervous matter ending abruptly on the front surface of the brain, 

 this extending backwards, and being joined by the stems of the 

 mushroom-bodies, and reaching nearly to the back of the brain, after 

 being gradually reduced in size. The heads of the mushrooms are 

 seen to be, as described originally by Dujardin, discs folded upon 

 themselves, and bent downwards before and behind. No doubt the 

 forms of these parts differ in the Bee and the Blatta, but still, in 

 their principal features, they are much alike. 



I cannot help thinking that, a model such as this gives a far better 

 idea of the true form of the internal parts, than it is possible to 

 obtain from a study of sections alone, and, indeed, even if these 

 minute structures are dissected out, there is great fear of their being 

 distorted in the process. But, after all, the great use of such models 

 is to enable the lecturer, or demonstrator, to convey to his 

 students a correct knowledge of the parts under consideration, and I 

 trust that this model may be the means of enabling some of us to 

 comprehend, more easily than we otherwise should, the complex 

 structures of an Insects' Brain. 



