Excerpt from Pathology and Morbid Anatomy Varieties of Disease - Distinguishing, as we have done, the liv ing olganism from its surroundings or environment, we see at once that mum of disease may be roughly classified into (a) those arising out of defects 1n the original constitution of the individual, or hereditary dis ease; and (6) those produced by abnormal or hurtful external circum stances, or acquired disease. Thus, on the one band, a person may be born with gross or min11te structural defects, rendering some organ in capable of performing its normal function; or certain of his tissues may be defective in that they rapidly degenerate or wear out. On the other hand, injury may be inflicted by external agents-by cold, heat, or mechanical violence, by poisons taken in with the food, or by the entrance of parasitic organisms. When, however, we look a little more closely into the matter, we find that no definite line can be drawn between these two classes of diseases. Thus a parasitic organism may be unable to establish itself in the body and induce dim except in the pres ence of some hereditary defect in resisting-power on the part of the individual; while those who are the subjects of manifest hereditary weakness may be able to survive if their surroundings are modified as premature babies may be reared in artificial incubators, or bleed cts may antler no inconvenience if protected from all possible sources of mechaniwl injury - the congenital defect consisting in a failure of these organisms to adjust themselves to ordinary external conditions, which in these cases are actually injurious. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.