272 MESSRS. F. GOTCH AND V. HORSLEY 



existence of degeneration furnishes us with positive evidence as to-the presence of a 

 direct path, its absence does not exclude the existence of such a path. 



The embryological method, which affords a very fair control of the degeneration 

 method, was instituted by FLECHSIG and has since been extended by BECHTEREW and 

 others. It gives a fair indication of the proportionate number or quantitative relation 

 of the elements which go to make up any one channel, whether direct or indirect, 

 but beyond this, and the all important localisation of position, it does not carry us. 

 By a special histological method, introduced by GOLGI, the anatomical relation of the 

 paths in the developing cord have recently received a fuller demonstration, at his 

 hands as well as KOLLIKER'S, RAMON Y CAJAL'S and others. 



It will be convenient to tabulate the facts according as they relate to 

 I. Centres. 



II. Paths. 



I. CENTRES. 



Functional Activity of Centres. 



As regards Centres, the position assumed in the introduction 4 ' is, we believe, as a 

 matter of fact, tacitly in the minds of observers, if not admitted, and the influence of 

 " basal centres" is not so overwhelmingly important as originally supposed by the 

 older observers. To conveniently combine, therefore, the results without doing 

 violence to the theoretical views expressed by anyone, it is only necessary to arrange 

 the facts in relation to the part which is the seat of experimental investigation. 



A. Cortex. 



(1.) Latent Period. The loss of time which intervenes between the application of 

 the stimulus to the cortex and the commencement of the resulting muscular contrac- 

 tion is -06 on the average in the Carnivora. (FRANCK and PITRES, BUBNOFF and 

 HEIDENHAIN, SCHAFER, ourselves.) 



(2.) Excitability. This property of the cortex is greatly altered, i.e., either in- 

 creased, or diminished by 



(a) Severe haemorrhage ; (b) deep anesthesia ; (c) cooling ; (d) drying ; (e) fatigue ; 

 ( /) peripheral stimulation of the functionally corresponding and other parts of the 

 body. (BOBNOFF and HEIDENHAIN, BCZZARD, EXNER.) 



The latent period may vary from the effect of any of these causes as well as from 

 the intensity of the stimulus. (BUBNOFF and HEIDENHAIN and other authors.) 



* Viz., that the plan of the central nervous system, as regards its " motor" side, consists in a cortical 

 mass of grey matter, and a corresponding mass in the bulbo-spinal part of the central neural axis, 

 with segmental representation of function, while that finally these two great central apparatuses are 

 connected by the direct paths known as the pyramidal tract or excitable fibres of the corona radiata 

 internal capsule, and, we must add, of the lateral column of the spinal cord. According to this view 

 the basal centres and corjbelluni act on the direct motor apparatus, if at all, as reinforcing mechanisms. 



