SECT. 115.] NERVOUS SYSTEM. 23 1 



continued farther, the fact could scarcely fail to be discovered on 

 careful inspection. Withdrawn from view, it is doubtful, on the 

 other hand, how they terminate. All I can sav is, that the fibres 

 of the nerve-bundles entering into the third division of the lenti- 

 cular nucleus, as may be directly observed in many preparations, 

 become gradually so fine that they measure only 0*0008'" to 

 o , ooo6'", or even 00004'" xxs - diameter, and appear almost quite 

 pale, so that they are scarcely distinguished from the finer pro- 

 cesses of the nerve-cells, with which, in fact, unless the whole 

 appearance is deceptive, they may in reality be connected. All the 

 fibres entering the nucleus caudatus present a corresponding arrange- 

 ment with those just described. One part of them proceed directly 

 from the base of the cerebral peduncle into the nucleus; the other, 

 entering its thinner part, obviously come from the nucleus lenticu- 

 laris, having previously passed through the two first divisions of 

 the latter. Here, also, there is no transition of these fibres into 

 the white substance of the hemispheres, but a separation of the 

 bundles into networks of the finest, almost non-medullary fibres, 

 and most probably a connection of the fibres with the cells. 



Besides the above-described, and, unquestionably, very numerous 

 nerve-fibres, which come from the cerebral peduncles and terminate 

 in the corpus striatum, the nuclei of the latter contain a consider- 

 able number of others, of whose origin it is difficult, and, in some 

 respects, impossible, to speak positively. I believe I can trace one 

 set of these tubes to their origin. In the outermost part of the 

 great nucleus of the corpus striatum, there is found in different 

 sections a considerable number of bundles of tolerable size, but 

 invisible to the naked eye, which are distinguished by their com- 

 parative thickness and the diameter of their tubes (from o - ooi2'" 

 to o"002'"), from the fibres of the cerebral peduncle, which are 

 here very fine and split up into networks. It is easy to see that 

 all these bundles come from the medullary substance of the hemi- 

 spheres, and that they enter the corpus striatum after, as it appears, 

 they have run for a certain distance at the border, and parallel to 

 the surface of that body. Many of these fibres also simply extend 

 from the medullary substance into the ganglia, and in this course 

 decussate with the former fibres at a right angle. All these fibres, 

 collected into bundles, penetrate into the grey substance of the 

 corpus striatum and the third division of the lenticular nucleus, 

 and then terminate, as I believe I have found, in narrow loops, 

 without forming expansions or plexuses, or suffering further 

 attenuation. 



