affected by these changes, and in addition, being forced to pump against increased resistance, hypertrophies to compensate. If overworked, as in a diseased condition of long duration, it finally fails to carry the additional burden placed upon it. The kidney, because of this high pressure, is forced to over-activity, resulting eventually in degenerative changes.

For the present discussion, the chronic conditions which are the sequelae of diseases such as valvular lesions of the heart, or an acute renal inflammation, may be ignored. Compared with those produced by irritation as just described, they are few in number.

Etiology.

The causes producing this vascular irritability and consequent high blood pressure may be grouped into three general classes, viz:

I. Environmental conditions which demand a persistent hyperactivity of the circulation.

II. Interference with the normal chemical changes of the body resulting in the retention of toxic substance in the blood.

III. Productive changes incidental to advanced age.

In the first group are included worry, excitement, overwork, especially of a mental character, much being the result of the stress of modern life as evidenced in our large cities. The tendency of a large part of our population to dwell in these great centers brings a vast number of people under these environmental influences. Abnormal expenditure of nerve force influences reflexly the vaso-motor nerves controlling the tension of the arteries, with resultant high blood pressure.

The second group refers to interference with the normal chemical changes of the body, and may be further divided into

(a) Substances introduced into the system which act as irritants. The excessive use of alcohol, the toxic products of the infectious diseases, `and the effect of metals, such as lead, as absorbed, for instance, by painters, are included in this sub-group. The pathological changes produced by Syphilis are characteristically productive and degenerative in type, and affect many organs such as the heart, blood vessels, kidneys, liver, brain and other parts of the nervous system.

(b) Over-eating and injudicious eating. Over-eating may have a direct mechanical effect by unduly working the circulatory system in its endeavor to distribute the material to the tissues, and to dispose of the end-products resulting therefrom. By injudicious eating is meant the excessive use of meats and other foods, especially of a heavy protein character from which by-products are evolved that act as irritants to the blood-vessels after their absorption.

(c) Digestive disorders, such as constipation, intestinal stasis and sluggish liver action which result in imperfect digestion of foods. Foods normally should be digested, absorbed and carried to the tissues without evil effects, but as the result of these digestive disorders, by-products of a toxic nature are evolved, taken up by the blood and thus irritate the circulatory apparatus.

(d) Imperfect renal elimination with, therefore, the retention in the system of toxic substances, which act not only as irritants of the muscular elements of the vessels, but poison the tissues themselves, thus directly promoting degenerative processes.

This direct toxic effect on the tissues applies to all the by-products referred to in the preceding groups.

The third general classification considers the changes in the cardio-vasculorenal apparatus in persons of advanced age, as part of a general sclerosis incidental to this time of life. In addition to the organs of circulation these changes are found in the liver, lungs, brain and other parts of the nervous system. Whether they are normal for this time of life is an open question, but at least we do know their development is the rule rather than the exception. It seems to be the penalty of old age.

Prevalence and Mortality.

These two subjects must be considered together, for in this disease the only statistical proof as to prevalence is that secured from mortality figures. Infectious diseases are required to be reported and directly provide a basis for morbidity calculations, but the existence of disease of the cardio-vasculo-renal type is not officially known except through death certificates. For the estimation of illness, however, we are discussing a type of illness which, once fully developed, has a fatal termination sooner or later; therefore, the mortality figures not only enable comparisons of deaths and death-rates to be made, but serve also as a fairly accurate index of the prevalence of the disease.

Facts, therefore, which are presented in the following tables, should be taken not only as proofs of mortality conditions but of morbidity as well.

Table I gives figures which were taken from the 1912 report of the U. S. Census Bureau. The total number of deaths in the Registration area were divided into 38 specified groups of causes. From these I have selected the five highest groups (all that were above 50,000) and arranged them in order of greatest number. Diseases of the arteries and other forms of Tuberculosis have been appended for comparison purposes. The number of deaths from Cerebral Hemorrhage and Apoplexy, Angina Pectoris, Asthma and Cirrhosis of the Liver, are also noted, because these diseases are the result of the same productive and degenerative processes that give rise to the chronic diseases of the heart, the arteries and kidneys.

It will be noted that heart disease heads the list, and if disease of the arteries is added thereto a total of 101,660 is reached, even exceeding the 93,396 ascribed to Pulmonary and all other forms of Tuberculosis. Heart disease plus Bright's disease plus arterial disease=163,027 or 20% of all deaths. If the allied group, including cerebral hemorrhage, angina pectoris, asthma and cirrhosis of the liver be included, the sum total is 223,834 or over 25% of all deaths. Table I-Deaths for 1912 in Registration Area of United States. Total Deaths

of which

Organic Disease of Heart

Pulmonary Tuberculosis

Bright's Disease

Violent deaths (except suicide)

Pneumonia

Diseases of Arteries, Atheroma, etc.

Other forms of Tuberculosis

Cerebral Hemorrhage, Apoplexy
Angina Pectoris

Asthma

Cirrhosis of Liver

.838,251

86,179 10.3%

78,465 9.4%

62,267 7.4%

53,729 6.4%

51,495 6.1%

15,481

14,931

45,752

4,391

1,588

8,176

In Table II are shown figures from the 1912 annual report of the N. Y. City Department of Health, which correspond very closely to the National computation. The Cardio-vasculo-renal group totals 16,718 or over 20% and adding in the allied diseases gives 18,928 or over 25%.

Having shown the large proportion of deaths in this group, the next step is to determine whether these diseases are relatively increasing or decreasing. Data extracted from the 1912 Census Bureau report are presented in Table III. Three other large groups, viz.: Pulmonary Tuberculosis, Pneumonia and Diarrhoea under two years of age, are included to show decreases as compared with the uniform increase in the cardio-vasculo-renal group. It is worthy of note that two of thèse decreasing groups, Pulmonary Tuberculosis and Diarrhoea, are those in which campaigns of public education are being systematically conducted.

Table III-Death Rates per 100,000 Population-U. S. Reg. Area.

Table IV quotes figures appearing in the 1912 annual report of the N. Y. City Health Department, from which the rates each tenth year from 1870 are taken. Heart disease and Bright's disease have been grouped together. The steadily increasing rate is very apparent, and in decided contrast to the decreasing rate for all deaths shown in the adjoining column.

Year

1870

1880

1890

1900

1910

1911

1912

Table IV-Death Rates-Former City of New York (Now Manhattan and The Bronx).

In an article entitled "Possibilities of Reducing Mortality at the Higher Age Groups," Dr. L. I. Dublin, Statistician of the Metropolitan Life Ins. Co., says: "It is necessary to concentrate attention on the diseases and conditions which cause the larger part of the mortality at the advanced ages. These include cancer, diabetes, apoplexy, organic heart disease, diseases of the arteries, cirrhosis of the liver and Bright's disease." His table relative to this statement is presented herewith as Table V. It will be noted that excepting cancer and diabetes, all the diseases belong to the cardio-vasculo-renal or allied groups.

Table V-Death Rates-100,000 Pop.-(Registration States of 1900).

Another table of Dr. Dublin's appearing in the same article is submitted as bearing upon the next step, which is to locate the age groups wherein these increases occur. This 1900-1911 comparison shows (1) the decreased rate of total deaths in 1911; (2) in males, a high ratio of decrease in the early years becoming less up to 45 years of age, at which point it changes to an increase and so continucs; (3) in females, the ratio of decrease is higher than males, and is thus maintained over a longer period of years, not being converted to an increase percentage until after 55. To further quote Dr. Dublin: "It is evident, therefore, that at all ages the mortality has been much more favorable for the females than for the males, but in both sexes, the various forces which have been at work to reduce mortality, suddenly lose their effectiveness during the period of middle life, at which time an actual deterioration occurs."

Table VI-Comparison of Mortality of Males and Females by Age Groups. Death-Rate Per 1,000 Population. (Registration States as constituted in 1900.)

Portions of one table While these classificaconcerned, still in the

Dr. W. H. Guilfoy, Registrar of Records, New York City Department of Health, in an article discussing mortality for the past 40 years, gives rates comparing the years 1868 and 1907, which are very striking. are presented to show circulatory and urinary diseases. tions include acute diseases with which we are not adult age groups the chronic forms are so predominant they well illustrate our point. In circulatory diseases, the steady increase beyond 30 years of age is very marked, with the same increase for the urinary group beyond 35 years of age.

Table VII-Death Rates-Per 1,000 Pop.-Former City of New York
(Now Manhattan and Bronx).