Sections made from such a case suggest still more that some excretion of lead has taken place from the bloodvessels, as the lead particles may be seen closely related to the capillaries; but here again there is little doubt that it is due to absorption from the externally inflamed surfaces of the gum rather than excretion of the vessels themselves. It is interesting to note that, in all the experimental animals, in no instance has any Burtonian line been observed, although the animals (cats and dogs) have been fed upon cat’s meat, which readily undergoes putrefaction, and organisms capable of producing sulphuretted hydrogen are invariably present in the mouths of such animals. Notwithstanding this, the blue line has not been observed, because the animals’ gums were entirely free from infection or pathological changes. By causing an artificial inflammation around the canine teeth of an animal exposed to lead infection, a definite blue line was produced in two weeks. This line had all the characteristics of the common Burtonian line. This form of blue line with a deep pigmentation of the whole of the gums, although in itself not to be regarded as diagnostic of lead poisoning alone, rarely occurs unless the person has been subjected to such long-continued poisoning that other symptoms have already made their appearance. The blue line, then, whichever type is observed, cannot in our opinion be regarded as a diagnostic sign of lead poisoning, but is merely an indication that the person who exhibits the phenomenon has been at some time or other subjected to lead absorption.