It is a matter of common observance, how eagerly dogs will lick up blood. That this is not to be ascribed to the nutritive value of the albumin-content of the blood is shown by the fact that when they are given their choice of meat or blood they will at once turn to the blood. There must, then, be a difference in taste, and, indeed, blood is distinguished by its salty taste. When we accidentally scratch our gums with a toothpick, we can easily convince ourselves of this fact.
Dogs often do not get enough salt in their food, and, since animals cannot talk, they cannot ask for it when their masters forget to give it to them. The salt contained in meat is often not sufficient for their needs, and other articles of food frequently contain even less or, like vegetables, for reasons which we shall give later,have a tendency to increase their desire for salt. The iron contained in the blood may also instinctively attract the animal, as his usual food is mostly very poor in this constituent.
We can often observe how wild dogs get over bones. Here again there can be no question of great nutritive value, even when we include the marrow, for they very often prefer the bones to the meat. It would doubtless be more accurate to consider the other substances contained in the bone, and, of these, lime is the most important. Very likely it is also the instinctive desire for and need of lime which impels the dog to eat bones.
Possibly the marked craving of cats for fish is due to similar reasons, and is related to the large amount of phosphorus contained in the flesh and bones of many kinds of fish. Cats are also very fond of milk, and here it is perhaps the phosphate of lime found in considerable quantities in this food substance which forms the principal attraction, in addition to the other nutritive components.
Owing to its considerable content of these substances, a milk diet is of the greatest importance for young growing animals or children, since the bones must be built up, and these consist principally of lime and phosphorus. When these elements are not present in the food, or are insufficiently rep-resented, growth is retarded, as has been shown by a number of experiments. The nutritive salts are necessary for both man and beast; we may even say that they are much more so than the food substances themselves, for without nourishment animals will live longer than when deprived of salts. Although the latter are not nourishing in themselves, the food ingested by us would be of no use whatever if it did not contain these salts, and when the quantity contained is insufficient marked disturbances of health occur. The special importance of these salts has been shown by the experiments of Forster, whose animals all died when placed upon a food from which the nutritive salts had been almost entirely removed. His experiments were confirmed by those performed by Lunin in the laboratories of Bunge. With the addition of sodium carbonate Lunin’s mice lived somewhat longer, but all finally died. For man, animals, and plants to thrive, it is necessary that they should have a sufficient quantity of the nutritive salts. While many of these important salts may be present in quite ample amounts, the health will suffer if one of themthe iron, for instanceis not sufficiently represented. Liebig’s law of the minimum amount is not only true in regard to plants, but of man as well, and we must see to it that precisely this element, iron, which is present in such small quantities, be supplemented by that contained in the food. Probably there is no function of the body which could be carried on without an ample supply of nutritive salts. Without their assistance we could not build up our bones and tissues, nor would any cell nuclei be formed; the osmotic tension in the blood and in the tissues would be impossible without these salts, and very often the action of ferments, too, could not take place. They have a very powerful influence upon all metabolic processes, and without their help the unpoisoning of the organism from the products of metabolism would not occur. Since the iron is the carrier of the oxygen, the oxidative processes in our bodies depend upon the presence of the nutritive salts, and Albu and Neuberg class these salts as “catalyzers,” i.e., place them in the same category, as regards their mode of action, as the ferments and enzymes. Neither the nerves nor the muscles could carry on their functions without the presence of certain ions of sodium, calcium, and potassium, and without them life itself would be impossible, as has been proven by the experiments of Forster and Lunin.
Thus, these salts exist in certain quantities in the body; the earth-salts preponderate; others, such as iodine and arsenic, are present only in very small amounts, but nevertheless play an important rôle, and, as has been so rightly said, even the most minute quantities may cause a sudden acceleration in the chemical processes which take place in our bodies. I would like here to cite the example given by the secretions of the ductless glands, several of which, like the adrenals, are only tiny structures weighing a few grams. The secretion of these glands, which is also very slight in amount, circulates in all the blood and is everywhere active. From all that has been said, it is plain how necessary it is that we should ingest these important salts, and this we can do by a judicious choice of our food substances. Nevertheless, it is not such a simple matter, for, in addition to the taking of the proper foods, it is also necessary that these nutritive salts should be absorbed, and, what is still more important, be assimilated, i.e., retained. For when, as may occur with the lime-salts, the greater part passes out through the intestines in the presence of intestinal disturbances, we have but very little use of the salts, and we must see to it that the elimination takes place through the kidneys, rather than through the intestines. With some of the nutrient salts, e.g., those containing phosphorus, the organic combinations may appear in the urine, while the inorganic are for the most part excreted by the intestine. Even when, however, the greater part of these salts is taken up by the blood, their assimilation depends upon the condition of those organs which regulate the general metabolic processes of the body. These organs are the ductless glands, and without their assistance we could derive no benefit from the nutritive salts which have been taken in with the food. The relations are here inter-changeable. On the one hand, the ingested salts, including iodine compounds, have a very stimulating effect upon the thyroid, and the taking of too much iodine may even give rise to Basedow’s disease ; on the other hand, the thyroid has such an effect with regard to certain nutrient salts, such as lime, phosphorus, and common salt (sodium chloride), that its over-activity may cause an increased elimination of these salts. When one of these ductless glands is inactive, as, for instance, the spleen, the iron contained in our bodies, as found by Ascher, is not assimilated, but is thrown off in large quantities. In my opinion, there can be no doubt that the entire mineral metabolism is governed and regulated by the ductless glands. These glands also form a sort of depôt for certain salts; the thyroid, for instance, contains the most iodine, which it gives off as required; the spleen seems to act in the same way for iron, and the pancreas for silicic acid. The adrenals seem to stand in relation with sulphur. In view of the great importance possible, in certain cases in which it was tried, to bring about considerable improvement; Kocher and Trachewski showed the same results in Basedow’s disease, by administering sodium phosphate.
In the treatment of epilepsy, similar results have also recently been obtained in the same way. It is, furthermore, of great importance to state thatas has been shown by experiments on animals and by clinical experiencewhen phosphorus is absent in the food polyneuritis and other conditions, such as beriberi and Barlow’s disease, occur, which are greatly improved by foods rich in phosphorus. Phosphorus can best be administered in organic combination, as demonstrated by the experiments of Roehmann and his followers, and also in a most convincing manner by those carried out upon children by Cronheim and Muller.
A certain way of administering plenty of phosphorus is to give the nucleins. (See the works of O. Loewi.) In this way nitrogen and phosphorus are provided. The same result was obtained by Buchmann by giving lecithin, which also increases the growth of animals (Stocklasa). The lecithins are fat-like bodies, which contain much phosphorus; they are found in grains, especially wheat, oats, and other cereals. The pollen of flowers also contains considerable lecithin, so that there is a certain amount of it in honey. Among animal foods, eggs, in particular, have a considerable lecithin content. Further-more, much of it is found in certain organs, especially in the liver; thus, when we eat calves’ liver we are taking in a considerable amount of lecithin. The same is the case when brains and milk are used as foods. However, woman’s milk is superior to cows’ milk, as the body is better able to take up and make use of its phosphoric content.
To what extent the phosphorus of lecithin-containing foods is assimilated is shown by the fact that 80 per cent. of it is found in the urine and 20 per cent. in the stools, which proves a most complete utilization. With a vegetable diet, there is a poor showing in regard to the assimilation of phosphorus; this is a great pity, since these foods often contain much of it; it passes off, however, together with the lime, through the intestines. In fact, in those living entirely upon a vegetable diet, much more phosphorus is found in the stools than in the urine, showing it has been very poorly made use of. It would therefore be very interesting to investigate whether the entire question of the condition of physical inferiority among vegetable-eaters, as compared with meat-eaters, which is noticeable even among birds, is not in some way related to these facts. Nevertheless, however much phosphorus we may be taking, even in the organic form, which is so much better absorbed and assimilated, its utilization in our bodies and its incorporation into the tissues for the maintenance of their functions depend greatly upon the condition of the thyroid and sexual glands, as well as the hypophysis. When the thyroid is overactive, much phosphorus is eliminated, as has been found by Roos and Scholz. On the other hand, as we have already mentioned, the elimination is lessened in underactivity of the thyroid. In order that phosphorus be properly assimilated, it is very important that the thyroid function be normal, i.e., neither over-nor under- active. With overactivity of the sexual organsthe ovaries, for instancethere is associated an abundant elimination of phosphorus and lime; the same occurs in osteomalacia, in which psychoses also make their appearance. When, however, these persons are castrated, the pathological elimination ceases. Curatulo and Tarulli found that when female dogs were castrated the phosphoric elimination was diminished; after the administration of ovarian extract, it was increased again. Castration in women may likewise cure osteomalacia, and the excessive output of phosphorus ceases; the fact that the administration of phosphorus will also cure this condition is of great practical significance (M. Sternberg, is, Sauerbruch). Phosphorus in addition influences the assimilation of lime; in osteomalacia it appears to do this in a roundabout way through the intermediary of the ovaries. In general, the nutritive salts, as we have already stated,’ act primarily upon the ductless glands, and the latter then regulate their use according to the various requirements of the organ-ism. When phosphorus is administered the lime can also be better made use of, and we therefore see an improvement in this respect in rickets. This disease, which affects so many children, seems to be due to the absence of lime-salts in their food, as has been shown by the experiments of Roloff and Baginsky, as well as those of Aron and Seebauer. Seemann found, too, that the milk of the mothers of rachitic children is often surprisingly poor in lime; Göttig, again, proved that with food poor in lime the bony structure in the limbs suffers, and an increased reabsorption of the bones may occur. The absorption of a sufficient quantity of lime may also be interfered with by intestinal disturbances. Even when an ample amount of lime has been taken in with the food and has been absorbed, rickets may, in my opinion, still occur if there is degeneration of the ductless gland, the function of which is to utilize the lime which has been ingested in accordance with the requirements of the various organs. It is an uncontrovertible fact that ossification of the epiphyses of the hollow bones does not take place even for some time after the age of puberty, when the thyroid or sexual organs (as in eunuchs) are degenerated ; and it is also well known that in degenerated conditions of the thyroid the formation of callus after fractures of the bones often does not occur. When, however, thyroid extract is administered, callus formation proceeds, i.e., a better reaction on the part of the tissues becomes evident. In my opinion it must therefore logically follow that, however great be the amount of lime in the food, it will not be sufficient for the cure of rickets, unless treatment by thyroid extract is instituted at the same time. Good results have thus been obtained in several cases; and if this fact has not been confirmed by others, it is because the other factora sufficient quantity of lime or phosphorus in the foodwas not combined with the thyroid treat-ment. Both these factors, the nutritive salts and organotherapy, must be simultaneously brought into play. The fact that the thyroid gland influences the growth of bony structures, as was first shown by Lanz, undoubtedly affords a solid foundation for the above statements.
The amount of lime present also greatly affects the blood, for in the absence of lime coagulation does not take place, since its influence is that of an activator of the coagulating ferment. The coagulation of milk by rennet is prevented in the absence of lime. The influence of the latter upon the functions of the brain is also of great importance, since the experiments of Sabatani and Quest have shown’ that an insufficiency of lime increases the irritability of the cerebral cortex, while an increase of lime lowers it. According to von Noorden, in rachitis, as well as in gout, administration of lime is very efficacious. Lehmann is of the opinion that lime increases the activity of the kidneys. From the above it will be seen how important it is to take plenty of lime in the food, which is best accomplished by the use of milk and drinking-water containing this sub-stance. Although many plants are very rich in lime, it is unfortunately a fact that, as has been shown by Bunge, this lime is much less readily taken up by the blood than that contained in meat foods. As stated by Roese, it is a great draw-back that, owing to the unskillful cooking of vegetablesit is more than unskilled; it is actually criminaland especially through allowing them to stand for a long time in tepid water, a very considerable amount of the nutritive salts is lost; they are simply soaked out. Roese also pointed out the very injurious effects of drinking water poor in lime; he found that wherever soft water is used many men are found incapable of the military service; the chest measurements, too, are smaller, and tuberculosis is very prevalent. If we consider the powerful influence exerted by lime upon the growth of the bony skeleton, this will be readily understood. We shall now present Bunge’s table of the amounts of lime and phosphorus contained in some of the commonly used foods.
As we may notice, yolk of egg and spinach are very rich in phosphorus and lime; they also contain a large amount of the salts of iron. These are also most important salts, since iron forms part of the blood-corpuscles, and has to transport the oxygen which has been taken up in the lungs by the blood-corpuscles to the tissues. It thus acts as the oxygen carrier.
Furthermore, it plays an important rôle in the formation of hemoglobin, and in this connection Bunge is of the opinion that the iron in organic combination is more effective than in inorganic compounds. Bunge and Abderhalden have shown that animals receiving food poor in iron become very anemic; when they are given a diet rich in iron, e.g., cabbage, carrots, and various greens, the iron-content in the blood is increased. As far as the absorption is concerned, there does not seem to be any material difference between the organic and the inorganic varieties; since, however, the former is absorbed more freely, it is a good plan to take in the necessary amount of iron with the food. If it is contained in sufficient quantities in the food, the inorganic preparations of iron may, when there is chlorosis or anemia, very powerfully excite the blood-forming organs. In fact it would seem, as I have already stated in my work, “Old Age Deferred,” that the action of iron is explained by the fact that it primarily excites to greater activity the ductless glands which govern the blood-forming bone-marrow and also the thyroid and sexual glands. When, therefore, we wish to prevent or cure anemia, we should, instead of taking expensive medicaments and artificial preparations of iron, eat foods such as blood-pudding, spinach, eggs, etc.
The observations of Ascher indicate that the condition of the spleen is of importance in the assimilation of iron in the body. He found that dogs from which the spleen had been removed eliminated more iron than healthy ones. The iron set free in the process of metabolism can be stored up in the body through the agency of the spleen; otherwise it is eliminated.
Again, sodium chloride is an absolutely indispensable nutrient salt. Herbivorous animals possess a veritable mania for it, and it is advisable in a cow-stable, for instance, to hang up a large piece of salt if one is not to see the cows licking all manner of objects in search of it. Sheep also thrive and stand the bad weather better out in the fields if sufficient salt is given them in their food. The diet of these animals contains a large amount of potash salts ; and Bunge has shown that when much potash is ingested in vegetable foods, much soda is withdrawn from the blood in consequence; this must then be made up again in the food. Thus, in eating potatoes, we require a great deal of common salt, since they contain much potash and very little soda; with rice, on the other hand, but little salt is needed, as rice contains but little potash salt. The passage of a large amount of salt is not at all good for the kidneys; they may be injured thereby. When the kidneys are diseased, very little salt is eliminated, as has been shown by Alexander von Koranyi, who introduced cryoscopy. H. Strauss, Vidal, and Achard have stated that the ingestion of much sodium chloride is very injurious, and may induce edema when the kidneys are already diseased; they found also that the edema was much improved when a diet very poor in salt was given.
H. Strauss found that when the kidneys. do not quite fully carry out their functions sodium chloride is retained, whereas the other chlorides pass through. It follows from the above that an excess of salt may injure the kidneys, but that it has no injurious action when small quantities are taken daily, and when the kidneys are healthy. A rice diet would perhaps be the best for the kidneys, if the rice were not, as is often the case, overseasoned.
Besides the important nutritive salts already mentioned there are several others, such as those containing iodine and arsenic, which, though they occur in minimal quantities only, are of much importance in our bodies. Iodine plays ‘a very great rôle because it is required by the principal ductless gland, the thyroid, for the carrying out of its functions. Iodine is absent from inactive thyroids, as also in the presence of connective-tissue goiters. The thyroid contains the most iodine, but the various other ductless glands, as well as the blood, also contain organically combined iodine; it is present, in particular, in the leucocytes. Iodine influences the various metabolic processes as a catalyzer. We take it in with our’ food. According to Bourcet, the vegetarian diet contains more iodine ; certain varieties of fish, such as the herring, also contain it in quite considerable amounts. Aron states that the thyroid gland contains about 1 centigram of iodine. Arsenic, too, is contained in minute quantities in various organs, according to Gautier and Bertrand. In eating hens’ eggs we absorb a small amount of arsenic. Silicic acid is also contained in our organs, and particularly in the muscle tendons. Schulz affirms that the connective tissue contains this substance in fairly large amount. It is an interesting fact that the iodine is contained in the thyroid, the iron in the spleen, whereas the silicic acid is especially well represented in the pancreas (Kali and Kunkel).