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27 for if the irritation had not been too severe, they recovered their full activity when resolution occurred.

Thus the pigment cells afforded ocular demonstration of the truth, to which I was otherwise led by inference, that an irritant, when producing inflammatory congestion, prostrates for the time being the vital energies of the tissues on which it acts.

It is to be observed that mere paralysis of the nervous apparatus of the irritated area would have been followed by diffusion of the pigment, as occurred after section of the nerves in the thigh, so that the suspension of diffusion as well as concentration shows that the special pigmentary functions had been arrested.