ON URTICARIA 



227 



articles as certain shell-fish, green fruit, or oatmeal, a very 

 short interval frequently suffices to produce the character- 

 istic rash and to set up the familiar local itching and 

 sensory disturbance, so much so, that ordinary bacterial 

 and physical methods seem far too slow to effect the 

 morbid changes. We are, therefore, driven by necessity 

 to contrive an explanation which will at once meet this 

 difficulty and be more or less scientifically satisfactory. 



The toxin, or materies morbi, contained in the articles 

 mentioned, whatever it be, must almost at once effect an 

 entrance into the blood stream, therefrom to be deposited 

 in the cerebro-spinal fluid, or possibly communicated to 

 certain neurons, and thereafter transferred by neural 

 circulation to the implicated peripheral nerve terminals, 

 where its presence is soon attended by stasis and accumula- 

 tion of the local neural lymph, with consequent elevation 

 of the overlying cuticle, and, it may be, more or less 

 lasting oedema, and possibly also associated capillary haemal 

 changes. 



On the exhaustion of the pathogenic influence of the 

 toxin, the effects of its attack, local and general, gradually 

 subside, frequently almost as rapidly as they were de- 

 veloped, leaving, it may be, a more or less desquamating 

 cuticle over the affected areas, and, it may be, a more or 

 less perverted innervation of the implicated terminal 

 nervature. 



Whether at the bottom of such local nervine patho- 

 logical phenomena there is temporary occlusion of the 

 neural excretory apparatus in the areas affected it is impos- 

 sible yet to say, but reasoning from analogy, there seems 

 at any rate reason for supposing that, besides an increased 

 arrival of local cerebro-spinal lymph, there is increased 

 difficulty of excretion of that lymph, with the inevitable 

 local elevation of the affected areas, ephemeral or more 

 lasting. 



The more intense and violent varieties of the affection 

 are characterised by the elevated areas assuming a more or 

 less papular and vesicular development, along with, it may 

 be, implication of the locally associated haemal vasculature, 

 consisting of a more or less pronounced erythema^ which 

 sometimes so completely overshadows the original nervine 



