382 SPECIAL HISTOLOGY. 



the medullary substance of the cerebellum itself, as a continuation of 

 which they are to be regarded. 



116. G-anglia of the Cerebrum. The three pairs of cerebral gan- 

 glia, the corpora quadrigemina, optic thalami, and corpora siriata, all con- 

 sist of bulky collections of gray substance, and of nerve-fibres ; the former 

 of which are in part quite isolated (corpus striatum), in part mutually con- 

 nected, and with more deeply lying portions of gray substance (thalami 

 opticij corp. guadrigemind) ; the latter connect the ganglia, on the one 

 hand with the cerebellum and medulla oblongata, and on the other with 

 the hemispheres of the cerebrum. 



The corpus striatum contains two large gray nuclei, the nucleus 

 caudatus anteriorly and superiorly, and the n. lenticularis posteriorly 

 and inferiorly, which are, however, connected in front, constituting a 

 single mass ; and besides these, the slender n. tceniceformis, with the 

 amygdalce external to the lenticular nucleus, and is in connection prin- 

 cipally with the basis of the cerebral peduncle or continuation of the 

 pyramid which expands in it, forming numerous white fasciculi. The 

 gray substance presents, as almost universally, nerve-cells and fine nerve- 

 fibres. The former, which measure from 0-006-0-018 of a line, are, in 

 part, colorless, and in part, contain pigment, as, especially, in the cau- 

 date nucleus and third segment of the lenticular nucleus ; they are fur- 

 nished with from two to five processes, and occur in greater numbers 

 according to the depth of color of the gray substance. 



The nerve-fibres may be referred for the most part to those of the 

 basis of the crura cerebri. They present the form of dark-bordered 

 tubes from 0-0012-0-005, most of them from 0-002-0-004 of a line 

 in size, which, running parallel and close together in a straight direc- 

 tion, enter the first division of the lenticular nucleus, and the most 

 anterior, thickest portion of the caudate nucleus. When traced further 

 in the lenticular nucleus, it will be seen that they form larger and 

 smaller fasciculi, decreasing somewhat in size (most of them measuring 

 from 0-0012-0-003 of a line) and that, passing straight through the 

 more scanty gray substance of the first divisions of the lenticular 

 nucleus, they are all ultimately lost, spreading out in a penicillar form in 

 its outermost and largest division. That is to say, white fasciculi mea- 

 suring from 0-04-014 of a line, with fibres of 0-0012-0-002 'of a line, 

 enter this division of the nucleus from the second ; and these fasciculi 

 in close contiguity, slightly diverging and subdividing into smaller bun- 

 dles, are continued further in a direction towards the outer border of 

 the lenticular nucleus, before reaching which they disappear to the 

 naked eye. If traced microscopically in preparations made with 

 chromic acid, it is apparent, that the fasciculi proceed nearly to the 

 outermost part of the lenticular nucleus, though gradually broken up 



