Page:Popular Science Monthly Volume 7.djvu/188

176 do not present unimpaired pathological evolution, but, on the contrary, furnish still additional instances of physiological development. It is chiefly, therefore, in cases of accidental sudden death from violence that the designed type of development (both pathological and physiological) can be studied best at all. But here, again, specimens of pathological evolution would occur less often than those that are physiological: first, because the whole number of pathological cases is less than the physiological ones; and, second, because individuals undergoing pathological development are less exposed to the liability of death by violence; they, like young individuals undergoing physiological evolution, require more rest, warmth, and frequent feeding, and are less strong and vigorous, than others whose physiological development has been completed, and who are, therefore, more disposed to cope with the risks and hardships of out-door life and labor, under which circumstances death from violence more frequently occurs.

At any rate, it is nothing else than an axiomatic proposition that similar organisms, impressed with similar stimuli, under similar circumstances, will lead to the development of similar structures. Now, it is evidently only by the rarest possibility that we could meet, in the civilized human subject, with a succession of instances in which all these conditions had prevailed. In man and domesticated animals, it is even observed that physiological growth differs widely, but, within certain limits, in different individuals of the same age, species, etc.: it is only in wild animals and plants that we observe uniformity of type; much less, then, need we expect to find this uniformity in evolutionary processes that are pathological; especially, too, when it is only sought for in man and domestic animals.

Finally, notwithstanding the difficulties I have mentioned, enough subservience to a fixed type on the part of pathological new formations has been observed, especially in cases where the new growth and its cause have been limited and simple, to warrant the assertion that pathological evolution in this respect is analogous with physiological development.

This analogy may be further established by considering various other disturbing conditions (in addition to cold) which act disastrously alike in the two kinds of evolution; but this may be reserved for a subsequent paper, when we may also present a new method of study, based upon the views herein laid down, and by the pursuit of which it is possible the nature, cause, and prevention of disease, may be investigated more after the manner of the exact sciences.