B. =Pathological Hypertrophy.=--3, 4. Instances of this are everywhere and every day are met in the results of so-called _chronic inflammation_, a term which is a complete misnomer and should be expunged from text-book use. So-called chronic inflammation simply means increase of nutrition owing to a certain degree of hyperemia, which may have been produced in the first place as the result of traumatism, which may have come from chemical irritants circulating in the fluids of the part--as, for example, uric acid, etc.--or which is brought about as the result of perverted trophic-nerve influence. Instances of local pathological hypertrophy may be seen in the thickened periosteum after injury, in the enlargement of a phalanx known as the “baseball finger,” and in numerous other places; or they may be general, in which case they are brought about mainly by some irritating material in the general circulation. The unknown poison of syphilis generally provokes such nutritive disturbances. 5. _Senile hypertrophy_ is connected with nutritional disturbances characteristic of old age, as to whose remote causes we are still uncertain. Instances of senile hypertrophy, however, are common, particularly in the prostates of elderly men, which are liable to undergo extensive enlargement. 6. Of _congenital_ hypertrophy and that of unknown origin we see, for instance, examples in certain rare cases of hypertrophy of the breast, in leontiasis, perhaps even in acromegaly, etc.; and these are to be distinguished from _gigantism_, because in most instances of the former type the hypertrophic tendency is not manifested until youth or adult life, whereas gigantism is a condition in which the tendency was apparent even before the birth of the individual. ATROPHY. _Atrophy implies impaired nutrition, and means diminution in the size of an organ or part_, and is the converse of hypertrophy. It is necessary to make plain that in atrophy nutrition is only impaired and not arrested, since complete arrest of nutrition means necrosis--_i. e._, gangrene or disappearance of parts. It may be-- {1. From disuse without disease; A. _Physiological_ {2. Biological or developmental; {3. Senile. {4. Result of acute tissue losses; B. _Pathological_ {5. Result of phagocytic activity; {6. Result of continuous pressure; {7. Specific.