Quarterly journal of microscopical science . explanation ofthe presence of these curiously definite structures. According to Duboscq (who examined Opisthopatuecinctipes, Purcell) one ran distinguish in these organs twodistinct regions, («) the vesicle, (b) the ganglion intermedia latter is the pari which former writers have called the stalkor peduncle of the vesicle. The term ganglion intermediateis unsuitable, especially since it appears that Duboscq himseli INFRA-CEREBRAL ORGANS OP PERIPATUS 411 is not sure whether the cells of this part are nerve-cells ormerely supporting cells. Ther
Quarterly journal of microscopical science . explanation ofthe presence of these curiously definite structures. According to Duboscq (who examined Opisthopatuecinctipes, Purcell) one ran distinguish in these organs twodistinct regions, («) the vesicle, (b) the ganglion intermedia latter is the pari which former writers have called the stalkor peduncle of the vesicle. The term ganglion intermediateis unsuitable, especially since it appears that Duboscq himseli INFRA-CEREBRAL ORGANS OP PERIPATUS 411 is not sure whether the cells of this part are nerve-cells ormerely supporting cells. There is nothing that might be termed the ganglion inter-mediare in Peripatoides occidentalis (Text-figs. 2and 3). The vesicle is described by Duboscq as containing nothingwithin the cavity but serous fluid, there being no refringentoval body of the kind referred to by Balfour. (UnfortunatelyBalfours figure gives no idea of the histology of the infra-cerebral vesicles.) Now we have found occasionally that Text-fig. 2. G - /// *lffiii»«i ..... Infra-cerebral vesicle, with enclosure, from adult Peripatoidesoccidentalis. x530. u, ganglion; v. infra-cerebral vesicle. bodies do occur within the cavity, reminding one of Balfoursdescription, and the Text-fig. 2 is from the best preparationof this character. It is part of a transverse section through thehead. The structure is referred to below. The infra-cerebral organs appear in dissections to hang fromthe supra-oesophageal ganglion by short stalks. In seel , they appear more closely attached. The differencein appearance is due to the transparency of the suspendingmembrane which is the structureless, almost non-staining,sheath of the ganglion. In Peripatoides occidentalisthere is generally a region that one might term the peduncle,within which are a few scattered nuclei and a small numbei 412 WILLIAM J. DAKIN of delicate fibre-like strands. They might be nerve-fibres or,on the other hand, merely processes of non-nervous cel
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