186 Observations on the Structure qft?ie Brain. 



layer of coarse granules, nearly of the diameter of the nuclei of 

 the bloodglobules, and similar to those which cover the flattened 

 extremities of the articulated fibres, at the surface of the cortical 

 substance of the brain. 



It remains still to be investigated, whether the knotted kind 

 of fibres are only to be found in the nerves above mentioned, or 

 are peculiar to all sensory nerves, while the cylindrical tubular 

 fibres are peculiar to motory nerves. 



Both the cylindrical and the articulated fibres, as they pass 

 from the brain into the roots of the nerves, receive a nervous 

 covering or neurilema, which invests each individual fibre, and 

 each bundle of fibres, as well as the whole trunk of the nerve, 

 with a dense cellular and vascular coat. 



The cylindrical fibres are stated to be about jj^ of a line in 

 diameter. 



It must not be supposed, that Professor Ehrenberg has con- 

 founded the tubular appearance of the nervous fibre with that of 

 the neurilema, for he professes to have accurately distinguished 

 the limits of both these parts. 



The Ganglia are described by Professor Ehrenberg as some- 

 what resembling the brain, in respect to the nature of the fibres 

 composing their nervous substance. They are formed by reti- 

 culated collections of both articulated and cylindrical fibres, in- 

 terspersed with granules and cellular texture. In some places 

 in the ganglia, he has also remarked a greater than ordinary en- 

 largement of the swellings of the articulated fibres. 



These observations have been made on the human brain and 

 on that of some quadrupeds, of birds and reptiles, with nearly 

 the same results in all. 



Chemical Analysis of an Indian Specimen of Mesolite. By 

 Robert D. Thomson, M.D. H.E. I.C.S. Communicated by 

 the Author. 



This specimen of mesolite I obtained in Caranja, one of 

 tlie picturesque insulated islands in the harbour of Bom- 

 bay. In this locality, as well as in Salsette, it appears to occur 

 in considerable abundance in amygdaloid, which bears a striking 



