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The writer believes that it always depends on secondary infection—i.e. that the vaccinal wound becomes the nidus of an erysipelatous contagium already existing in the patient's surroundings, just as any other traumatic surface might, and that the vaccinal virus has nothing whatever to do with it.

Richardson believes that the contagium was attached to the thatch, which could not be thoroughly disinfected.

That the contagium of scarlet fever may be received into the system and cause pharyngitis, while the patient has immunity from scarlet fever through a previous attack, and that this inflammation may occur any number of times, as in the case of Dr. Wood, are remarkable facts.

That these minute bodies really constitute the virulent element of the lymph, or at least that they are the vehicle of the contagium, is not a mere matter of conjecture, but has been demonstrated abundantly, notably by Chauveau and Sanderson's diffusion experiments.

Furthermore, whether associated or not with an organic substance, the contagium of the disease is known to preserve the power of reproducing itself for a period lasting for weeks, months, and even a longer time.