THE SYSTEMIC NERVOUS SYSTEM 31 



out of it without "leaving a trace behind" to mark its 

 passage, but, if not inducing secondary diseases of a more 

 or less fatal character and persistent nature, which leave a 

 wreckage, it may be of a permanent kind. 



In like manner such diseases as the following primarily 

 incubate in the cerebro-spinal lymph, and, secondarily, 

 affect its surrounding, containing and contained, tex- 

 tures, viz. Variola, vaccinia, varicella, scarlatina, measles, 

 cerebro-spinal meningitis, trypanosomiasis, rheumatic fever, 

 eczema, a great proportion of the non-febrile cutaneous 

 eruptive affections, at least those of an internal microbic 

 origin, as well as many less definite or anomalous and 

 ephemeral affections, which " come and go" comparatively 

 unnoticed. 



These may be looked upon as types of bacterial disease 

 whose habitat is primarily the cerebro-spinal lymph. 

 Another class, however, may find an entrance to the true 

 nervine structures from this medium, of which we may 

 enumerate such affections as plumbism, arsenical neuritis, 

 alcoholic neuritis, and beri-beri, with those cases of 

 chemico-physical origin whose manner and method of 

 attack and spread are still enrapt in great obscurity. 



The meningeo-neurilemmar structures are liable to 



O 



attack by their own specific ailments, as well as indirectly 

 by those of their contained fluid, while in like manner 

 the true nervine structures are affected by their own 

 intrinsic ^diseases, as well as indirectly by those of their 

 surrounding and enclosing fluid, and outer solid or 

 organised envelopes. 



The diseases, therefore, which affect the nervous system 

 partake more or less of the pathological characters of these 

 three elementary structural constituents, in varying pro- 

 portions according to the nature of the materies morbi, 

 its manner and method of attack, and the evolution of 

 the morbid phenomena constituting the various diseased 

 conditions. Thus one, two, or all three, may be impli- 

 cated in the same disease, each of which may leave its 

 pathological impression individually or conjointly in the 

 features of the particular disease, and the sequence of its 

 symptoms in its evolution as well as involution. 



The nervous system may, from the foregoing remarks, 



