980 CUTANEOUS SENSATIONS. 



the severer analgesia is on the same side as the severer lesion, but touch has 

 remained good on both sides. This agrees so far with the path traced by 

 Schiff and Budge to short fibres of the spinal root that plunge into the grey 

 horn. The continuation of the path cannot, however, remain long in the grey 

 matter, because the grey matter may be quite destroyed, and hollowed out at a 

 level, and yet no complete analgesia result in the parts further below the site of 

 the lesion. 1 The path therefore leaves the grey matter soon after entering it. 

 In the grey matter a column cell must be introduced into the chain of conduc- 

 tion, because section of posterior roots leads to no degeneration that goes 

 through the grey matter and on into the white beyond. 2 Laehr 3 points out, 

 on the basis of the Brown-Sequard paralysis, that in certain such cases the loss 

 of sensation on the side opposite to the loss of motility is a loss of pain and 

 temperature sensation. The conduction upwards of impulses producing vaso- 

 motor reflexes Avas found by Miescher 4 and myself 5 to occur in the ventro- 

 lateral parts of each lateral column. It has been suggested that the ventral 

 division of the cerebellar tract (Gowers' tract) is a pain-path. 6 It may be so, 

 although the connection with the cerebellum does not support this suggestion ; 

 yet, because part of the tract ends in the cerebellum, it does not follow that all 

 of it does so. But we do know that the ventral cerebellar tract is partly crossed. 

 There is the bundle of crossed fibres, described by Grunbaum 7 (by degenera- 

 tion after median longitudinal section), lying at the periphery between the two 

 cerebellar tracts. Its upward destination is unknown. Even if the pain-path 

 employ these crossed fibres, the pain fibres of the roots do not transgress the 

 median line of the grey matter, but end on their own side. It is quite 

 possible that the path is partly crossed, partly not. The tautomeric segmental 

 effect of the lesions confined to grey matter, and the crossed herniana3sthetic 

 effect of the lesions which include white matter, indicate clearly that outside 

 the grey matter is a collected strand of pain fibres, reinforced from segment to 

 segment by contributions from column cells in the grey matter. The main 

 path so formed may likely enough be a crossed path, but there seems to be an 

 uncrossed as well. Gowers has recorded a case in which a unilateral haemor- 

 rhage in the lateral column at the upper cervical region produced complete 

 analgesia and thermansesthesia of the opposite side, without disturbance of 

 touch. The path of conduction for warmth impressions, it is suggested, lies 

 near to but is not entirely commingled with that for pain. 8 



The above statements suggest strongly that there is in the spinal 

 cord a more or less distinct "pain-path," into which the impulses 

 generated at certain " skin spots " enter with comparative ease. Among 

 the features of the path are these : It is less open than others to 

 reactions of moderate and brief kind, that is, it requires stimuli 

 intense or long-continued ; the efficiency of stimuli that are long-con- 

 tinued is due to the high degree of summating power possessed by the 

 path ; the path is largely a crossed path, and soon enters, crosses, and 

 leaves the grey matter; in doing so a column cell is intercalated in the 

 conduction chain. What is the relation, if any, of this path to impulses 

 subserving the pain initiated by deep organs ? Is it a skin pain-path or 

 a path for sense pain in general ? There is a good deal of evidence in 

 favour of the conduction of the centripetal impulses from muscles by the 



1 M. Laehr, op. cit.; also Schlesinger, op. cit. 



2 Singer, Sitzungsb. d. Ic. AJcad. d. Wissensch. , Wien, 1882, Bd. Ixxxiv. Abth. 3 ; 

 Tooth, Goulstonian Lectures, Lancet, London, 1889, vol. i. ; Mott, Brain, London, 1895, 

 vol. xvii. ; Mott and Sherrington, Proc. Roy. Soc. London, 1895, vol. Ivii. 



3 Op. cit. 4 Op. cit. 5 Op. cit. 



6 Gowers, "Diseases of the Nervous System," London, vol. i. 



7 Journ. Physiol., Cambridge and London, 1894, vol. xvi. ; see also Mott, Brain, 

 London, 1895, vol. xvii. 



8 H. Schlesinger, op. cit. 



