MAMMALIAN. 53 



The connection of the auditory nucleus with the flocculus is very eA'iclent, as has 

 already been noticed by Schroder van der Kolk, who attributes to it the " particu- 

 larly large size of the flocculus in the Eodentia, which are possessed of acute hear- 

 ing."^ In the cat the flocculus is also very large, corresponding with the great 

 development of the auditory root (Fig. 35, Plate IX), the latter sometimes, especially 

 near its entrance, being quite bent out of its course and pushed in towards the facial 

 by the size of the flocculus (Fig. 36). The connections between it and the auditory 

 are very strikingly evident; just along the posterior portion of the network constitut- 

 ing the outer nucleus of the auditory, a row of large multipolar cells is found, inter- 

 mingled with which are many of an oval, fusiform or semilunar shape, following 

 each other quite closely and regularly, from which a very beautiful fringe of fibres 

 proceeds, turning over and forming a very regular and conspicuous band which may 

 be traced into the flocculus, where its flbres join the bundles radiating into the con- 

 volutions of the cerebellum. 



In the sheep (Fig. 12", Plate XVI) this connection is easily made out, though 

 not quite so conspicuous as in the cat, where the size and regularity of the cells, 

 together with the formation of thick bands of fibres which are very easily traced, 

 leave no doubt of the fact. 



In the upper portions of the medulla, the connection of the whole posterior 

 part of the auditory nucleus with the cerebellum becomes more and more mani- 

 fest. As we ascend, the outer portion of the nucleus together with the restiform 

 body is gradually thrown backwards into the cerebeUumj very numerous fibres 

 from the inner portion of the nucleus arching over the fourth ventricle and meeting 

 those from the opposite side, so that the valve of Vieussens together with the lingula 

 is inclosed as it were, or overarched by these fibrous expansions, which, as Clarke 

 has shown,^ pass over the superior pedtincle to the inferior vermiform process. 



The fibres from the central and outer portion of the nucleus spread out in 

 every direction into the substance of the cerebellum, especially towards the 

 corpus dentatum,, and finally (Plate XIV, Fig. 16") the nucleus, together with the 

 restiform body, is thrown far back into the substance of the cerebellum. The further 

 destination of these fibres, which, Avhether derived from the auditory nucleus or 

 the cerebellum, certainly serve to connect the two, and to bring them into very 

 close relation, deserves carefid study, but could hardly be entered upon without at 

 the same time studying the anatomy of the entire cerebellum, in order to determine 

 whether the connection is with the larger lobes, or only with those more nearly 

 contiguous. The connection of the large cells near the apex and in the outer net- 

 work, with the auditory roots, is very easy to demonstrate, as well as their connec- 

 tion with fibres emanating from the restiform body and cerebellum. In Plate XII, 

 Fig. 41, we have a group of large multipolar cells from near the entrance of the 

 auditory roots into the apex of the nucleus, from the medulla of the cat, drawn with 

 all possible accuracy by means of the Camera Lucida. Bundles of entering fibres 

 from the auditory root are seen {A, A, J.) running inwards towards the cells, which, as 

 will be seen, take every variety of form and send their processes in many difi"erent 



» Medulla Oblongata, 115. = Proceedings of the Royal Society, 18G1. 



