DUBLIN MICROSCOPICAL CLUB. 193 



Mr. Mackintosh was indebted to Professor A. Agassiz for the 

 portion of the spine from which the section was taken. 



The Pseudo-electric Organ of the Bay. — Mr. B. Wills 

 Eichardson exhibited transverse and longitudinal sections of the 

 so-called electric or pseudo-electric organ of the Ray, and 

 observed that at one time the organ was considered by some very 

 distinguished observers to be structureless. This, to him (Mr. 

 Bichardson), was surprising, when he considered the compli- 

 cated beauty of the sections, and the facility with which they 

 could be made. The organ was one of those bodies occasionally 

 met with the whole arrangement of which would escape 

 observation were the sections too thin. He (Mr. Richardson) 

 had some that were cut to such extreme tenuity with the freezing 

 microtome, that portions of the cells into which the organ was 

 subdivided were shaved off. It truly was most complicated. Ex- 

 amination of the longitudinal sections would show that the 

 organ was divided into numbers of cells of somewhat oval shape, 

 and apparently of uniform capacity. The transverse or cross 

 sections, on the other hand, showed that these cells, so uniform 

 when viewed in the longitudinal slice, varied in shape when cut 

 transversely, or at right angles to the long axis of the organ. 

 Each cell seemed complete in itself, and was arranged thus: — 

 There was first a layer of capillaries that formed, as it were, a 

 deep vascular wall, which occupied or bulged into about half the 

 cavity in the longitudinal direction. This could be seen 

 distinctly in the longitudinal sections only. Removal of the 

 capillaries disclosed a layer composed of broad, loosely interlaced 

 fibres, formed of connective tissue, crossing which in various 

 directions were seen flat branching fibres of extreme tenuity, 

 possibly nerve cords. Finally, and apparently covered by this coarse 

 fibrous structure, there was a delicate translucent membrane, in 

 which vast numbers of exquisitely fine fibres ramified and formed 

 a loose network, in the meshes of which were scattered minute 

 and for the most part oval, granular, darkish corpuscles, that 

 gave ofi" numerous radiating, inosculating fibres, of relatively 

 great length. Those bodies were probably connective-tissue 

 corpuscles. This delicate translucent structure was composed of 

 two, or possibly more, layers, in one of which the stellate 

 processed corpuscles were chiefly situated, whereas in the other 

 there were imbedded, at very regular intervals, nucleolated 

 corpuscles, having well-defined margins. The greater number of 

 these were round, the remainder oval ; the round reminded 

 one of the nuclei seen in the delicate membrane of the cells of 

 the electric organ of the Malapterurus he exhibited at the 

 last meeting of the Club, but the nucleolus of each of the 

 latter appeared to be more distinct. The nucleus itself, however, 

 was smaller than that seen in the Ray. The remaining walls 

 of each cell, with which the structures so described were con- 

 nected, were composed of close-set fibrous tissue. The sections 

 were stained with carmine and mounted in glycerine. Mr. 



