warming, because so much heat escapes up the chimney and is not utilized in warming the house. If convective heat is used to warm the house up to a certain temperature, and the livingroom filled with light and warmth by an open fire, a very satisfactory condition of the temperature in living-rooms will be secured without a large increase in cost.

LUMINANT HEAT.

We have almost banished luminant heat from our houses. The light of our fires is hidden under a bushel-like stove, or buried in some secret furnace pit in the cellar, and not placed in the Scriptural position where "they which come in may see the light." We need to study nature's plan of warming, which is by associated light and heat. We do not often get the start of nature in our methods, and when we do we usually find ourselves going in the wrong direction. "Walk in the light" is sound theology and good hygiene. We do not secure in our living-rooms enough of this association of heat and light which we find in nature's plan as seen in the solar ray. The marriage of heat and light gives health as their offspring. What God hath joined together in nature's plan let not man put asunder in warming his home.

VOL. XXXI.-32

THE PERSONAL FACTOR IN THE ETIOLOGY OF PREVENTABLE DISEASE.

BY ALFRED LUDLOW CARROLL, M.D.,

NEW YORK.

It is a mere truism to state that preventive medicine is necessarily dependent upon our knowledge of the etiology of disease, and that its improvement as a practical art must advance pari passu with the increasing accuracy of such knowledge. Unfortunately, notwithstanding the excellent detective work which has been done with regard to general insanitary conditions, we are still in almost complete ignorance of the special origin of any of the morbid phenomena with which sanitary science has to deal.

In all preventable maladies, at least two factors are to be considered: the exciting-it may be specific-cause, and the susceptibility of the individual. Of the latter, particularly in relation to disorders of the zymotic class, but little note is taken or information possessed.

Some specific contagia, such as smallpox, measles, etc., "breed true;" although even here we find some persons resisting and others succumbing to the same exposure. In these, moreover, there enters, apparently, a third factor, formerly spoken of as an "epidemic constitution of the atmosphere," increasing individual receptivity of contagion, and turning the scale between sporadic and epidemic prevalence. I am aware that many epidemiologists explain the recurrent waves of contagious zymoses by the hypothesis that, one epidemic having exhausted the susceptible material in a community, a fresh generation of unprotected persons must arise before the same disease can again commit general ravage. But the frequent occurrence of sporadic cases in the intervals, serving as possible foci of infection and yet with little tendency to extension, and the fact that during epidemic years second attacks of the same malady are oftener

reported, seem to indicate the operation of some occult predisposing influence. The advent of cholera is commonly heralded by a proclivity to simple diarrheal disturbances; in scarlatinal outbreaks non-specific angina is unusually apt to effect even protected persons; an increased liability to catarrhal troubles seems to attend an epidemic of measles; et sic de similibus.

In other cases, however, specific variations in the manifestations of a common morbific agent appear to be determined by the peculiar proclivities of different patients; e.g., from "sewer gases" or contaminated drinking water may arise diarrhoea, septic dysentery or typhoid, quinsy or diphtheria, erysipelas, the "patchy" form of pleuro-pneumonia, etc., according as the patient's throat, respiratory or digestive organs may be most susceptible.

I know that I am at variance from some of my hearers in assuming the pythogenic origin of several of the disorders which I have named; but a tolerably wide experience for some years past in sparsely settled rural districts, where individual circumstances can be more readily ascertained, and accidents of importation of contagia more rigorously excluded, has afforded me repeated and convincing evidence of the origination of both typhoid and diphtheria from excremental pollution of either water or air. There is a constantly growing belief that even scarlatina may be generated de novo by filth poisoning under certain somatic conditions of which we are as yet ignorant. We know that diphtheria prevails most during childhood, when the tonsils and larynx are the most vulnerable points, and that a marked proclivity to it is shown in particular families with hereditary tendencies to other forms of sore throat. The same observation applies to other inherited or acquired susceptibilities to peculiar forms of disease.

Even under the "germ theory," this view of a personal factor as modifying the specific development of an implanted microphyte is tenable, since it is almost certain that various forms of fungous vegetation (as in the case of apparent species of puccinia, uredo, etc.) arise, not from any specific difference in the original germs, but from "the modifying influence of the circumstances under which they are developed ; and it is easier to imagine that the universally present germs of bacteria, etc, are influ

Carpenter on the Microscope.

enced in their mode of growth by the pabulum which they find in different unhealthy conditions of the animal system, than to believe that there are separate specific bacterial germs of ty phoid, diphtherial, pyæmic, or other character, always lurking in ambush for possible victims.

The "alternation of generation," so to call it, of pathogenetic virus is farther exemplified in the puerperal state, where the pelvic receptivity stamps a peculiar type of infection upon contagia arising from erysipelas, scarlatina, or ordinary sepsis.

The brief time at our disposal precludes elaboration of the argument; but, out of many illustrative examples in my notebooks, I may be permitted to cite two or three of the more striking ones:

I. A cottage situated on the shore of the Kill von Kull, in an aristocratic neighborhood, having its private drain emptying into the river. Drain obstructed and escape of sewer gas into house. Repeated attacks of diarrhoeal troubles at first; after two or three months a severe case of erysipelas in one member of the household; another lapse of a few weeks and two inmates were almost simultaneously seized with quinsy. Summer, with its open window ventilation, passed without serious illness; but early in the ensuing autumn a case of enteric fever was developed under circumstances which excluded the possibility of an imported contagion. Finally, a few months afterwards, a second and fatal attack of erysipelas fell upon the same patient who had previously suffered from it. These cases occurred in a family comprising five adults. Another tenant, with two young chil dren, shortly afterward moved into the house, and very soon the children (up to that time in robust health) were on my hands, at one time with diarrhoea, at another with obscure febrile symptoms, again with tonsillitis, until, as the landlord. failed to make the necessary repairs, I advised removal to other quarters, with the result of a rapid restoration to perfect health.

II. A house on an unsewered avenue in New Brighton; unventilated cesspool; water-closet in a windowless sort of pantry between bedrooms on second floor; insufficient flushing-water and unventilated soil-pipe. Family, including servants, four adults and one delicate child. First, minor diarrheal disturbances and general malaise; then scarlatina in the child, who had neither been away from the place nor received suspicious visitors. (All my efforts were fruitless to trace contagion through