ON THE MAMMALIAN NERVOUS SYSTEM. 419 



result and interpretation exists as that of the relations between the columns of the 

 cord and the passage of afferent impulses. 



The contradictory facts set forth in the various papers on this subject are sufficient 

 to justify the belief that many of the experiments made must have involved the 

 presence of some factor of capricious character and uncertain action, common to most 

 of them, and that the conclusions which the various experimentalists have drawn from 

 their results are all vitiated by its presence. 



When such a fundamental matter as that of the extent to which the afferent path 

 lies on one or the other side of the cord is answered so differently that, according to 

 one set of investigators (BuowN-SEQUARD, FERRIER, &c.), it is wholly crossed ; 

 according to others chiefly crossed ( WOROSCHILOFF, MIESCHER, &c.); equally uncrossed 

 and crossed (VAN DEEN, STILLING, &c.); chiefly uncrossed (VON BKZOLD, MOTT); wholly 

 uncrossed (CHAUVEAU); it is plain that the method adopted is at fault and is quite 

 inefficient for the purpose of determining the extent to which particular tracts in the 

 cord are concerned with the passage of impulses. The reason why the different 

 results of former investigators are so conflicting may, we think, be gathered by the 

 careful study of the experimental method in two of the most elaborate of the series 

 of investigations just referred to, those, namely, carried out in LUDWIG'S Laboratory 

 by MIESCHER"" and WOROSCHILOFF.+ 



Although the experiments are well known to physiologists, we think it necessary 

 to allude in a little detail to their character. Both sets of experiments were carried 

 out on Rabbits, and in both the method consisted in the production of an intervening 

 localized destruction of a portion of the spinal cord, and in then ascertaining what 

 changes this destruction produced in the reaction of some more central portion of the 

 nervous system of the animal to the stimulation of the afferent nerves of the distal 

 portion. The reaction observed was, however, different in the two cases, it being in 

 MTESCHER'S experiment the rise of blood pressure due to the activity of the so-called 

 vaso-motor centre of the medulla being awakened ; in WOROSCHILOFF'S, the movement 

 of the upper limbs of the animal, due, as he believed, to the awakening of a convulsive 

 centre in the medulla. The index used by MIESCHER being the amount of blood 

 pressure, had the great advantage that it varied with the strength and duration of 

 the afferent stimulation, and thus a quantitative comparison between the results of 

 two series of stimuli was possible, and it is, perhaps, due to this that the facts have 

 been held as affording data of so cogent a character. They show first that the 

 reaction of the centre, as indicated by rise of pressure, is very largely reduced when 

 the lateral column on the opposite side of the cord to that of the excited sciatic nerves 

 has been divided ; and second, that when a complete intervening division of the 

 cord, with the exception of one lateral column, is made, the reaction still persists, 

 being most marked when the distal nerve on the side of the complete section is 



* 'Ber. d. Sachs. Ges. d. Wiss., Math.-Physik. Cl.,' 1870. Also ' Arbeiten a. d. Phys. Lab.,' Leipzig, 

 t ' Ber. d. Sachs. Ges. d. Wiss., Math.-Physik. Cl.,' vol. 26, 1874. 



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