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XXXIV] If the weakened liver is efficiently inoculated at one point only, there is only one abscess ; if at many points, then there is multiple abscess. This is virtually, in a sense, Budd's theory expressed in modern terms.

An apparently weighty objection to this view is sometimes urged. Why, it is asked, if liver abscess be the result of septic absorption from a dysenteric ulcer, is it not a common sequel of typhoidal or of tuberculous ulceration in the tropics? McLeod has met this objection very ingeniously and, I believe, to a certain extent, correctly. He points to the fact that typhoidal and tuberculous ulcerations are surface lesions unattended with abscess formation in the wall of the bowel. In their case there is free escape of the products and germs of ulceration; whereas in dysenteric lesions, in addition to the superficial ulceration, there is often what is really abscess formation with burrowing and retention of pus below the mucous membrane, and therefore great liability to entrance of micro-organisms into the radicles of the portal vein. Liver abscess, therefore, according to this view, is a pyæmic process. Often, however, it must be confessed, the dysentery preceding liver abscess appears, judging from the symptoms, to be of the catarrhal rather than of a more severe type ; but even in this case it may be that the amœba penetrates the portal radicle without producing ulceration. To what extent the amœba is concerned in the production of tropical liver abscess it is as yet impossible to state. If the frequency of its presence is any indication it must be the usual if not the only cause. If we watch the movements of this animal on the warm stage; and if we reflect that it lives and wanders about in the same very active way among the structures forming the walls of the liver abscess, and even in what are comparatively sound tissues, preceding, as it were, the suppuration, or rather, the necrotic process; and consider that it lives at the expense of these tissues, it is hard to resist the conclusion that the amœba must operate as a disintegrating and irritating agency.