INFRA-CEREBRAL ORGANS OF PERIPATUS 



411 



is not sure whether the cells of this part are nerve-cells or 

 merely supporting cells. 



There is nothing that might be termed the ganglion inter- 

 mediare in Peripatoides occi den talis (Text-figs. 2 

 and 3). 



The vesicle is described by Duboscq as containing nothing 

 within the cavity but serous fluid, there being no refringent 

 oval body of the kind referred to by Balfour. (Unfortunately 

 Balfour's figure gives no idea of the histology of the infra- 

 cerebral vesicles.) Now we have found occasionally that 



Text-pig. 2. 



Infra-cerebral vesicle, with enclosure, from adult Peripatoides 

 occidentalis. x 530. g, ganglion ; v, infra-cerebral vesicle. 



bodies do occur within the cavity, reminding one of Balfour's 

 description, and the Text-fig. 2 is from the best preparation 

 of this character. It is part of a transverse section through the 

 head. The striicture is referred to below. 



The infra-cerebral organs appear in dissections to hang from 

 the supra-oesophageal ganglion by short stalks. In sections, 

 however, they appear more closely attached. The difference 

 in appearance is due to the transparency of the suspending 

 membrane which is the structureless, almost non-staining, 

 sheath of the ganglion. In Peripatoides occidentalis 

 there is generally a region that one might term the peduncle, 

 within which are a few scattered nuclei and a small number 



