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XIV. " Notes of Researches on the Intimate Structure of the 

 Brain." Second Series. By J. LOCKHART CLARKE, Esq., 

 F.R.S. Received June 20, 1861. 



In consequence of the frequent interruptions to which I am ne- 

 cessarily exposed in the course of my anatomical investigations, I 

 beg to communicate to the Royal Society, in the form of notes, some 

 of the results at which I have arrived, with a promise to forward, in 

 a few months, a complete memoir on the same subject, with the 

 necessary illustrations. 



In my memoir of the " Medulla Oblongata," it is shown that the 

 post-pyramidal ganglion, or grey substance of the posterior pyramid, 

 is developed from the posterior grey substance on each side of the 

 posterior median fissure. At the point of the calamus scriptorius, 

 it is intimately connected with the pyriform nucleus of the vagus 

 nerve, each receiving a process from the other. Between these two, 

 and apparently developed from the substance of both, which are 

 intimately blended with it, there arises a convex and somewhat trian- 

 gular mass, which becomes the principal nucleus of the auditory 

 nerve. In a transverse section it is triangular, one of its angles 

 projecting forwards into the root of the caput cornu posterioris, or 

 expanded extremity of the posterior horn. It is interspersed with 

 numerous large nerve-cells, which are round, oval, triangular, or 

 otherwise irregular, and of considerable size, the largest measuring 

 the 800th of an inch in diameter. Another portion of the auditory 

 nucleus is in contact with the outer side of that just described, and 

 with the inner side of the restiform body. It consists of the outer 

 part of the posterior pyramid in the form of a remarkable network, 

 enclosing in its meshes longitudinal fasciculi, and containing large 

 nerve-cells with branched and exceedingly long processes, which 

 contribute to form the network. From both these parts of the nu- 

 cleus the posterior division of the auditory nerve takes its origin, and 

 winds outward as a broad convex band over the restiform body. In 

 this course it contains, at first, a few small cells, elongated in the di- 

 rection of its fibres ; but as it proceeds, its cells become gradually 

 larger and more numerous, until at the anterior border of the resti- 

 form body it enlarges into a pyriform ganglion, which is crowded 



