Aside from the cells of the adipose and connective tissue and of various organs, the fat seems also to occur in a finely divided state in some tissues and in the blood serum. Thus Valentiner found in the macroscopically normal muscles (from the centre of the pectoralis major) of three corpulent persons, hard drinkers, 3.9 to 4.9 per cent. of fat, while the same tissue from three other marasmic individuals yielded only 1.3 to 1.7 per cent. According to different observations, fat in the blood of corpulent persons can be recognized even macro scopically by the milky turbidity of the serum, but according to Becquerell and Rodier this seems to occur chiefly in drunkards.
The adipose tissue of man, which liquefies at 20 to 25° C. and solidifies below 12 to 15°, contains the glycerides of oleic and pal mitic acids, with but little stearic acid; the composition changes, however, with the age of the individual. The fat of the new-born, according to Langer, contains more palmitic and stearic acids, and less oleic acid than that of the adult; its melting-point is therefore higher. But the melting-point differs also according to the organs in which the fat is deposited: it is highest in the fat of the kidney, lower in that of the subcutaneous tissue, and lowest in the fat accu mulated in the liver.
Whether there is a qualitative difference in the composition of the fat iu the various forms of obesity has not yet been determined, al though it does not appear improbable and has even been ascribed by some authors to special etiological factors.
According to Langer's investigations the composition of the fat at different ages varies; that of the new-born contains about three times as much fatty acid, palmitic and stearic acids, as that of the adult, and he places its melting point at 45° C., while that of the adult liquefies at 36° C. Moreover, the fat of young brandy drinkers, ac cording to Rokitausky, is said to be distinguished by an uncommon tallowy hardness and to approach in its quality some of the. animal fats such as mutton tallow. The experience of cattle breeders shows that the fat differs with the food supply, and they call it in the one case good or healthy and in the other bad or unhealthy. Quite a considerable difference in the nutrition of plethoric and anaemic corpulent persons exists also in the quantity and quality of the diet and is perpetuated in the utilization of the varying material in digestion, transformation, and deposition. There is moreover in
anaemia and hydrmia a greater fat-formation by restriction of the oxidation processes in consequence of the deficiency in haemoglobin and the accumulation of water in the blood and tissues. The experi ments by Munk and others to determine the results of feeding differ ent kinds of fat, especially mutton tallow, linseed oil, rape oil, etc., are likewise of interest in the settlement of this question.
The Blood.—The abnormal conditions of the blood in the various forms of corpulence, plethora, anmnia, and hydrmia, can be dem onstrated clinically, pathologico-anatomically, and by the direct de termination of the specific gravity, the haemoglobin contents, the density, and the proportion of water.
Although we have no figures in proof of a true plethora, yet clini cal and anatomical facts point indisputably to the presence of such a quantitative anomaly of the blood. Individuals in whom we are forced to assume the existence of plethora have, as shown in the symptomatology, a full, strong, tense pulse, a pronounced disposi tion to congestions, exhibit hypermnia of the external skin and the mucous membranes, a marked tendency to hemorrhages, especially in the brain and lungs, by reason of greater or lesser rise of blood pressure. At the autopsy we find a considerable amount of blood, together with hypertrophy and dilatation of the heart in consequence of the persistently increased demands upon it; while the circulatory apparatus is under an abnormally high tension, even when the in creased amount of blood is compensated for by enlargement of the heart (dilatation). Hence we find in the entire vascular apparatus clear evidence of a larger mass of blood which fills it, and it should be especially noted that the blood-vessels, like the heart, adapt them selves to the volume of the blood. In plethoric persons the vessels are greatly dilated as far as the capillaries, and their walls are thick ened, while in chronic ammnia they appear narrowly contracted and thin-walled. The differences are most marked in the thickness of the wall and the width of the aorta, which in the plethoric is found three or four times as wide as in the anicinic.