486 



ganglion is not always the same. This result has surprised me very 

 much, since if any organs might have been expected to be almost 

 invariable, I should have thought it would have been the nervous 

 system. I believe that no parallel case has been described, nor do 

 I even remember to have seen a description of any variation occur- 

 ring in the larger nerves of any animal whatsoever. Considering, 

 however, how great are the variations which occur here in the same 

 species, it is evident that differences in the distribution of the nerves 

 in nearly allied forms are in themselves no proof that such species 

 were separately created. 



Around the ganglionic masses are several large spherical bodies. 

 These appear to be homologous with the " Zellenkorper," described 

 by Leuckart as surrounding the supracesophageal ganglion in the 

 larva of Melophagus. He considers them also as homologous with 

 similar organs which have been observed in the embryos of other 

 insects by Heroldt and Kolliker*. 



Dujardin (Ann. des Sci. Nat. 1850, 3rd ser. vol. xiv. p. 202) de- 

 scribes the suprao3sophageal ganglion of the worker-ants as consisting 

 of several isolated parts, and I was at first inclined to consider these 

 spherical bodies as also merely isolated parts of the ganglionic mass, 

 in favour of which view it may be urged that fewer nerves than 

 usual appear to proceed from this mass. The contents of the 

 spherical bodies, however, under the influence of reagents, present 

 an appearance different from that of the supracesophageal mass. 



The suboesophageal ganglion is very richly supplied with tracheae, 

 derived from two large stems which are attached to the front angles, 

 and ramify from thence all over the mass. 



The supracesophageal ganglion is a triangular mass with its apex 

 behind. The two front corners terminate in large nerves. 



The nervous system of C. persicce differs but little from that of 

 C. kesperidum, and offers the same extraordinary amount of 

 variation. The two species, however, could be at once distinguished 

 by the superior size of the suboesophageal ganglion in C. persicce, in 

 which species also the last pair of nerves (fig. 10) is given off more 

 posteriorly, while both they and the central stem are considerably 

 swollen at their origin, so as to give the hind margin of the ganglion 

 a three-pronged outline. 



* Die Fortpflanzung und Entwickelung der Pupiparen. Halle, 1858. 



