HARDWICKE'S SCIENCE-GOSSIP. 



107 



that they might be taken to pieces, as in the process 

 ■of cutting sections, and the surfaces thus exposed 

 were coloured to represent the sections as they appear 

 under the microscope. 



This method of modelling was capable of still 

 further development. Having modelled the opposite 

 half of the brain upon the same plan, I drew upon 

 each of the model sections, thus produced, the out- 

 lines of the more important parts, as shown in the 



--& 



an— 



— oj> 



-~ z ~-=~ml 



-si 



no — - 



conv- 



Fig. 94. — View from the outer side of the 

 left half of model of upper part of brain of 

 Cockroach. The oblique lines in this and 

 fig. 95 indicate the successive slices of 

 which each is composed, op, cut end of 

 optic nerve ; an, cut end of antennary 

 nerve. 



diagrams (fig. 93), and these were then cut out in the 

 same manner as a child's dissected map-puzzle. Now 

 it will be obvious that by taking from each of these 

 " dissected" sections, the part, for instance, which is 

 in the diagrams (fig. 93), marked (<r),'and joining' them 

 together in their relative places, we shall have a 

 model of that particular part ; and by joining, in like 

 manner, the dark masses, and those marked (a), (/«), 

 (j/), we shall obtain models of the mushroom-bodies, 

 with their stems, etc. 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. 94), 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- 95)- 



I was in hopes that, before reading this paper, I 

 should have been able to construct 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 down- 

 wards 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 sec- 

 tions alone, and, indeed, 

 even if these minute struc- 

 tures 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 insect's brain. 



com j 



Fig. 95. — Right half of model-brain seen from 

 the inner side, with the parts dissected 

 away, so as to show the anterior nervous 

 mass, a ; the median mass, m ; the mush- 

 room-bodies, mb ; and their stems st. The 

 cellular cap, c, has been raised, so as to 

 display the parts below ; com, is a part of 

 the commissure to the lower portion of 

 brain, or infra-ossophageal ganglia. 



BOTANICAL WORK FOR MAY. 

 British Batrachian Ranunculi. 



SOME ten years ago we could not (perhaps being 

 a little prejudiced) believe that all Babington's 

 water ranunculi were specifically distinct ; however, 

 time has wrought a wonderful change in our opinions ; 

 we now look upon them as a beautiful series of 

 examples, all differing in some degree, yet linked 

 together to form one harmonious whole ; we hope to 

 carry this conviction home to all our readers. We 

 have often been surprised to find so few of our 

 botanists who seemed to care to study these plants, 

 and yet they all confess they should like to know 

 more about them ; now let us endeavour during the 

 present month, to search anew every pond and ditch 

 in our neighbourhood, and carefully compare speci- 

 men with specimen : we shall all be astonished at the 



