Not only is poverty, with its social and unhygienic consequences, a great factor in disease of the adult, but also is it of the greatest impor tance to the child, especially the infant. The hest environment for man consists of pure air, even temperature, sufficient and cleanliness. These are the most favorable hygienic conditions and are the essential factors for the maintenance of health in children. In view of this, it is not to be wondered that poor children show a much greater morbid ity and mortality than do those in better circumstances. Insufficient nourishment is another harmful influence which predisposes children of the poor to disease.
the other hand, we see that overfeeding may be harmful by producing an aphysiological stimulus. It is, however, a source of danger which attacks chiefly the children of the well-to-do. The work of Czerny must be looked upon as of great service in proving the injurious results of overfeeding. This is very common at present, with the exaggerated and over anxious care of children among the well to-do, and can scarcely be too strongly condemned.
Diseases of Infancy.— The difference between the infant and the adult has been shown; also the distinction between the pathogenesis of infancy and that of later years. In the second year of life, when the child begins to crawl about and speak and when its diet approaches that of the adult, the pathogenesis will be seen to depend, not so much on the internal as on the external influences. These external conditions are many. Escherich has referred to the importance of filth infection ("Sehmierinfection -) in the pathogenesis during the period of first dentition. The importance of this dirt infection is enormous, in the genesis not only of tuberculosis but of all other forms of infectious dis ease.—stomatitis, angina, diphtheria, whooping-cough, and intestinal parasites. Escherich's idea is, that the growing curiosity of the teeth ing infant, with its ability to crawl around and put dirty fingers into its mouth, has produced another group of diseases. This group is called by Peer but Escherich prefers the name "Schmierinfection," thinking it is a better way to explain the method of transmission. The factor of "Schnderinfection' must be taken into consideration, with the increased opportunity for eontagium at this time of life, because children, at least those of the poor, are thrown together very intimately on the streets. at the play-grounds, etc., and even sleep together in the same bed.
We should like to point out at this time another cause which may be of importance in the genesis of tuberculosis. This depends on the fact that tubercle bacilli may often be inhaled. The small child who has its mouth and nose closer to the floor dwells, so to speak, in an atmos phere which is much more laden with dust and tubercle bacilli than is that normally breathed by the adult, three feet higher. The chance for tubercular infection being the greatest between the first and second years of life, it naturally follows that the frequency of tuberculosis, as investigations have shown, suddenly increases between the years of two and four.
Tuberculosis is seen to exist in adults most frequently in the form of phthisis. but in childhood it tends to localize in the lymphatic system. This fact has not been well explained as yet. One imagines that it depends on the peculiar susceptibility and power of reaction of the lymph-nodes. What we have considered as scrofula these many years is often seen to develop into tuberculosis. There are many authors, who maintain that there is a non-tubercular form of scrofula. This seems to us no longer tenable, in view of the experience of lIeub tier, who declares in the last edition of his manual that all the eases of scrofula examined by him gave a positive test to tuberculin.
Diseases of the fifth and sixth years of life the peculiarities of children approach more closely those of the adult. Pathogenesis, dependent on the life of the child, at this time in school, now limits itself almost entirely to external 1111111011CCS. NerVOUS disorders appear as a result of mental work, scoliosis of crooked sitting and myopia from reading and writing in insufficient increased intercourse of this period presents a good oppor tunity for the transmission of infectious diseases, awl the mutual mental intercourse and psychical influences offer an opportunity for the ap pearance of certain nervous hysterical diseases. Of course, the proper predisposition must be present. In other respects, pathogenesis ap proaches that of the adult. Escherich shows how the crowded busy existence of to-day predisposes to certain traumatic diseases, -the in creasing occurrence of appendicitis, etc. Tuberculosis, especially that of the lymph-nodes,. is less often seen, the disease in general approaching, that of the adult. Certain new and dangerous diseases of infectious origin are seen to appear at this acute rheumatism, endocarditis, and chorea. The diseases at this period differ from the same in later life only in their course, just as we found so many did in the periods of first dentition and school life. The diseases appearing at this time (adolescence) are largely found among young girls. These are commonly chlorosis,---of the etiology and pathogenesis of winch little is known to-day,—and certain hysterical diseases. Twn diseases belong to this period of adolescence, which usually appear for the first time in the fifth decade of life. It is believed that they only appear after prolonged and persistent damage has been done, practically never if the etiological factors have been working only a short time. These two diseases are arteriosclerosis and gout. Diabetes is considered to occur only under the same conditions and so is found to be rare among children. The extraordinary rarity of malignant tumors in children is hard to explain, and can only be discussed on theoretical grounds without any practical or experimental evidence.