around the barn and dairy that they cannot be kept out of the milk by any degree of care. 4. The bacteria which produce the abnormal or unusual fermentations, like slimy milk, bitter milk, etc., are, however, not so common but that they may be prevented from entering the milk in sufficient quantities to produce serious trouble. 5. Filth is ordinarily their source, and cleanliness the means of avoiding them. 6. The souring of milk cannot be prevented, even by the greatest cleanliness. 7. Salicylic acid, in proportions of 1 to 1000, may be of some little value in delaying the souring, but its use is not to be recommended except in special cases. 8. Milk can be entirely deprived of bacteria by the exposure to a temperature of from 15° to 20° F. (8.3° to 11.1° C.) above that of boiling water, or by a long-continued boiling, or by a series of short boilings on successive days. 9. Such milk has the taste of boiled milk. This taste appears at about the temperature of 160° F. (71.1° C.); hence has arisen the method of Pasteurization of milk. By this method it is heated to a temperature of 155° F. (68.4° C.) for a short time, and then cooled. This greatly delays the fermentations, and also kills the pathogenic germs that may be present. 10. In our large cities the popularity of sterilized milk is rapidly increasing, especially given to patients troubled with diseases of the digestive organs. 11. The cooling of milk immediately after it is drawn from the cow is of the greatest assistance in delaying the fermentation, and in the present state of our knowledge is, probably, the most practical method which can be recommended. 366 B.32, H.4 GASTRIC DIGESTION. Troitzky, in a valuable paper on gastric digestion in small children, comes to the following conclusions: 1. The presence of completely coagulated casein in the stomach does not warrant one in speaking of the excessively acid contents of the stomach, for a precipitation of the casein from the solution can only happen in consequence of the influence of labferment, and this acts in the presence of an alkaline reaction. 2. The change of the casein, which has begun to coagulate, to the state of solution with subsequent peptonization, is due to the simultaneous action of acid and pepsin, and the stomach takes up the albumen the more successfully and completely the more the quantity and composition of the digestive secretions approach the normal. 3. Lactic acid must be Digestion. regarded as a normal constituent of the gastric juice; at least, in very young children and in those with whom the diet is exclusively one of milk. Its formation is encouraged by the milk-sugar which is abundant in the milk. This constant presence of lactic acid has its effect alike upon the digestive process and upon the action of microbes. 4. Hydrochloric acid plays the principal part in digestion, but its determination is not always easy, because the casein of the milk has the property of holding it. Until digestion begins, hydrochloric acid may usually be found in small quantities in the stomachs of very small children. As digestion increases in activity the quantity of hydrochloric acid will also increase. 5. The quantity of acid in the gastric juice of children is relatively very much smaller than in adults, and is conversely as the quantity of food taken into the stomach. 6. The average time during which food stays in the stomach of small children is two hours. 7. Slight mechanical, thermic, or chemical irritation of the gastric mucous membrane will increase the acidity of the secreted juice and favor a rapid emptying of the stomach. Alcohol stays digestion, but counteracts fermentation. 8. The part in digestion which is played by the stomach of the child is an important one, even though it does not appropriate all the albumen which comes into it. 9. The antimicrobic properties of the gastric juice are undoubted, and are due to the presence of free acid, especially hydrochloric acid. In consequence of the slight acidity of the gastric juice in the stomach of children, it cannot act as forcibly to retard fermentation as the same secretion in the adult. 10. It has not yet been determined what significance certain micro-organisms have upon digestion. 11. Functional disturbances in the stomach of children are due to changes in the quality and quantity of the gastric juice, the regular exchange in its ingredients being disturbed, or the parts being subjected to physical or chemical changes which are not yet understood. 12. The quantity of gastric juice in the stomach of children may be lessened without necessarily causing an increase of lactic acid, or the appearance of acetic or butyric acids. 13. When the normal secretion of the stomach is deficient, acids are developed which are not suitable for normal digestion. 14. The presence of too much mucus in the stomach may paralyze the digestive activity of the gastric juice, though the latter may be normal as to quantity and as to composition. 15. If too much food enters the stomach, or if it remains there too long, an insufficient quantity of gastric juice will be secreted for its digestion. 16. The majority of gastric dyspepsias in children are caused by the deficiency of hydrochloric acid in the gastric juice. Functional disturbance is rarely caused by excessive secretion of gastric juice. 17. Diseases of the stomach with definite anatomical peculiarities manifest themselves by the presence of an abundance of mucus, serum, and inflammatory elements. The severer the disease and the longer it lasts, the more conspicuous will be these elements. 18. With inflammation of the gastric mucous membrane digestion is reduced to a minimum, even though the gastric juice remains normal in quantity and quality. 19. Disturbed digestion is accompanied by the appearance of an increased number of fermentation phenomena, with the formation of acids foreign to the stomach and its work, as well as by the breaking up of albumen and the formation of decomposition products. The substances which are submitted to fermentation are the fats and the excess of mucus, which ordinarily do not undergo such changes. 20. A diminution or failure in the presence of hydrochloric acid in the stomach signifies the formation of pathogenic elements in the soil favorable to such development, the antimicrobic power of a sufficient quantity of hydrochloric acid being wanting. 21. It is quite possible that certain forms of micro-organisms, or their products, are responsible for the different diseases in the stomachs of children. The means for treating the abnormal conditions of the stomach, which has been found extremely efficient in numberless cases, is irrigation. Heubner, 366 B. gives the following analysis of the acids of the gastric juice during digestion in infants: The children who were the subjects of the investigation were nursed at the breast, or with cows' milk, or with milk-foods, or with albuminoid fluids, some being in good condition and some being athrepsic. The analysis of the gastric juice, which was drawn from the stomach at different periods after the ingestion of food, was made as follows: The juice was filtered, distilled, and deprived of its volatile acids; ether was added, to remove the lactic acid; then it was once more distilled and once more filtered. By Hoffmann's method, the quantity of free hydrochloric acid was determined. The quantitative determination of volatile acids was made twenty-three times in children 9 weeks to 11 months old. In 5 cases the quantities were appre ciable, in 7 there were traces, and in 10 there was none at all. The examinations were made three-quarters of an hour to an hour and a quarter after the ingestion of milk. The ages of the 7 children in whom traces of volatile acids were found varied from 9 weeks to 12 months, some being nourished at the breast and others with cows' milk. The juice was examined three-quarters of an hour to two hours after the beginning of digestion. Of the other 10, there were 5 who were nourished at the breast, 2 with diluted cows' milk, 2 with milk-food, and 1 with fluid albuminoids. The juice was examined from five minutes to two hours after eating. In 24 cases the examination for lactic acid was made. In 4 it was wanting, the ages varying from 11 weeks to 8 months, and the children being fed,-1 with Nestlé's food, 1 with fluid albuminoids, and 2 with a decoction of salep. Traces of it were found in 6, whose ages varied from 11 weeks to 1 year, 3 of them being nourished at the breast, 2 with cows' milk, and 1 with milk-food. In 11 infants from 9 weeks to 11 months old appreciable quantities were found, 4 of the children being nourished at the breast, and the others with cows' milk or milk-food. The quantity of lactic acid did not increase with the duration of the digestion. Free hydrochloric acid was sought in 46 cases and found in 12. The foregoing facts confirm the statements of Leo, who explains the frequent absence of free hydrochloric acid in the gastric juice of infants by the property which milk possesses of combining with hydrochloric acid, and so failing to appear in fluids that are examined. Hydrochloric acid is found in the free state in children when the combining force of the contents of the stomach is rapidly exhausted, as in cases in which children are given a decoction of salep. GROWTH AND AGE. BY CHARLES SEDGWICK MINOT, M.D., BOSTON. 178 Charles S. Minot, has published the results of an extended statistical investigation of the growth of guinea-pigs. The paper is to be followed by others, all bearing upon the general problem: What are the essential phenomena of growing old? or, as it may be termed, of senescence. Senescence is a property of most, perhaps of all, living matter, and so far as known has no parallel in non-living matter. Minot selected guinea-pigs for his experiments, because, amongst other advantages, they are inexpensive to purchase and keep, bear confinement well, and are but little liable to disease. They were kept during the summer months in spacious pens in the country, and in winter in large boxes, in warm, well-lighted and ventilated rooms. To measure the growth, the weights were taken of the growing and adult individuals, the weight being, in his opinion, the only available measure for the whole animal and the only one permitting comparison between different animals. Each animal was accordingly weighed every day from birth up to the fortieth day, then every fifth day up to two hundred and fifteen days, and after this period every thirtieth day. In regard to the conditions at birth, it was found that the number of young in each litter varied from one to eight; but litters of one, two, three, and four were by far the most common, and he thinks that two may be regarded as the normal number, which corresponds to the number of teats. The number of young tends to increase with the number of previous pregnancies, and is greater also in warm than in cold weather. In regard to sex, of one thousand guinea-pigs born, four hundred and fifty-six are females and five hundred and forty-four males. In the spring and summer there is a relatively greater tendency to the production of females. The average weight of a |