518 DR JAMES W. DAWSON ON 



the above abstract shows, Dr Bruce found in disseminated sclerosis a disease which 

 in his view accentuated the fact that in certain cases the effects of the causal agent 

 fall especially on the lymphatic system. He was one of the first in this country to 

 point out that in many cases the peri-ventricular sclerosis is the most important 

 lesion in this disease, and that it frequently dominates the macroscopic and micro- 

 scopic pictures. He formed the opinion that the lesions in the ependymal and peri- 

 ependymal tissues are probably of especial significance, and he argued that the 

 existence of such marked lesions around the ventricles raised the possibility of the 

 cerebro-spinal fluid having toxic properties and that the causal agent entered along 

 the lymphatics in the peri-venous sheaths. At the same time the peri-vascular 

 distribution of the areas in the central nervous system led him to recognise that 

 the causal agent might also be disseminated by the blood channels. He was strongly 

 convinced that the process was toxi-infective, and that the plaques were caused by a 

 gradual infiltration of the tissue with toxic lymph passing from a central focus, and, 

 while recognising the limitations of the method, he hoped that the careful histological 

 investigation of the morbid anatomy of the disease might ultimately throw light on 

 the nature of the morbific agent which is at work. 



Since Dr Bruce' s death I have worked up more fully the cases on which our 

 earlier joint observations were founded, and I have also investigated a considerable 

 mass of new material which has more recently been available. This material includes 

 a case which is of special importance from the fact that a full clinical record taken 

 under Dr Brtjce's personal supervision is in existence, and also on account of its 

 having a fatal issue after a comparatively short course. This more recent work, 

 and especially the observation of the acute case alluded to, brought new facts to 

 light, and necessitated a reconsideration of some of the earlier conclusions. 



It is a pleasure to acknowledge my indebtedness to the family of the late Dr 

 Bruce not only for the use of the material which belonged to him, but also for con- 

 tributing to the expense of the research, and in particular to Dr Ninian Bruce for 

 help in relation to certain points in pathological physiology and for reading the 

 proofs of the paper. 



During three of the years I have been engaged in this work I held a Carnegie 

 Fellowship, and I desire to thank the Trust for the assistance given and for generous 

 grants towards expenses and towards the cost of illustration. My thanks are also 

 due to the Committee of the Royal College of Physicians' Laboratory, Edinburgh, for 

 the facilities afforded for the research, and to Professor Ritchie, the Superintendent 

 of the Laboratory, for his sympathetic interest and criticism throughout the in- 

 vestigation. The coloured illustrations have been prepared by Mr Richard Muir, 

 of the University Pathological Department, and the micro-photographs by him, by 

 Mr William Watson, of the Royal College of Physicians' Laboratory, and Mr 

 Thomas Hamilton, my laboratory assistant ; my acknowledgments are due to all 

 of them for the care and skill they have exercised in executing the work. 



