380 



Dr. A. D. Waller. 



[Mar. 17, 



There occur in consequence of excitation from A to B and from 

 B to A— 



response from C to A no response from C to B, 



i.e., the electromotive spot has in each case been situated at or near the 

 external surface A. 



(2.) The subcutaneous tissue, and the corium itself, give no response. 

 A slice taken from the sole of the foot and limited to the horny layer 

 gives no response. A slice of skin taken so as to include the Malpighian 

 epithelium gives more or less well-marked response. 



And in this last connection I think it worthy of remark that the 

 response is well marked in specimens of skin that did not include any 

 distinct glandular masses. In the pads of the cat's foot e.g., where I 

 had expected to have to reckon with glandular as well as cutaneous 

 epithelium, it was evident on microscopic examination that no glandular 

 tissue was present, but only some scattered ducts belonging to deep- 

 seated glands. The principal active part was clearly the deeply 

 stainable layer of Malpighian epithelium. 



The Reaction is Local. — The blaze reaction of the skin is exclusively 

 local, and is not propagated to a distance from the excited spot. And 

 as regards physiological state, it generally happens that closely 

 adjacent portions may exhibit very different degrees of vitality. This 

 has been particularly apparent in the case of mangled skin and of skin 

 involved in cancerous growth. In both these cases it was not difficult 

 to distinguish correctly between skin likely to give a poor reaction and 

 skin likely to give a good reaction. But by reason of such local 

 differences it is not easy to obtain satisfactory instances of declining 

 vitality with lapse of time by taking the reaction of a series of 

 different bits of the same piece of skin; in general, a decline was 

 evident, but with frequent exceptionally low values at an early stage 

 and exceptionally high values at a late stage — e.g., No. VI on the sixth 

 day gave +0*0100 and +0*0150 volt to single shocks — an exception- 

 ally high value at this period. 



Nevertheless, it is possible with care to distinguish amid such 

 irregularities the general decline of skin vitality with lapse of time 

 and the individual differences of vitality in different skins of men and 

 animals. 



As regards animals, I have, however, made as yet only occasional and 

 unsystematic observations upon cats and rabbits, from which I have 

 provisionally concluded that the skin of man is more enduring than 

 that of either cats or rabbits ; that the skin of cats is more resistant 

 than that of rabbits, and that the skins of individual cats and rabbits 

 exhibit considerable differences of endurance according to the state of 

 nutrition at the moment of somatic death. 



I have been much astonished, and am still somewhat incredulous, of 



