The effect of captivity may also be felt in the direction of reduced resistance to infectious diseases. Brooks, of the New York Park, expresses the view that captivity increases susceptibility to bacteria and causes parenchymatous degenerations. In the latter direction it is interesting to learn that Seligman of London claims to have seen sudden deaths in wading and struthious birds from myocardial disease, without valvular or other lesions, for which he holds the enervating effects of captivity responsible. It is well recognized that a species may be unusually susceptible to a disease that it has not encountered in its phylogenic development. Man illustrates this peculiarity very clearly. Europeans were found exceedingly susceptible to sleeping sickness when they went first to the part of Africa inhabited by the tsetse fly, and the American Indians died in hordes when they met the tubercle bacillus for the first time. Judging by the ravages of tuberculosis in captive monkeys a similar susceptibility probably explains the matter for there are no entirely satisfactory records of this disease among them in the wild state. In so far as general susceptibility to infection is concerned, it may be in part due to one of the artificial conditions of captivity, that of inbreeding. This influence is undoubtedly very great, both by chance in families, and by intention on the part of dealers as well as the mating which occurs in menageries. However, it is not known how far inbreeding may go in the wild state so that one must be very careful about drawing conclusions in this particular. Several years ago, at the time we reported the neoplasms found at the Garden, discussion arose as to the effect of inbreeding, and thereafter some observations were made in this direction. With the exception of the hyperplasias of the thyroid, not certainly of neoplastic nature, in a much mixed-up family of wolves, we could find no evidence that inbreeding was responsible for tumors. Plimmer and Murray of London, seem to imply that some of their inbred animals are likely to have tumors; reference to this matter will be made later in this book. In so far as diseases of the organic systems are concerning those of the bones seem to be the only ones in which inbreeding is significant. The individual resistance will be reduced of course by the unsanitary surroundings incident to trapping, shipping and storage, but this need not affect the figures or pathological tendencies of classes or orders.