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FURTBER OBSERVATIONS ON THE NATURE OF FECES FAT.’ HT J . H. L O N G
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Received ?.fay 31. 190:.
I n two earlier papers figures were presented showing the amount of phophorus contained in the normal feces fat of a number of individuals. From the conditions of the experiments this phosphorus content, and t h e nitrogen found at the same time in one set of examinations, suggested the presence of a body or bodies of the “lecithin” type, using this term in the broader sense as describing the fat like “phosphatides” or “lecithans.” Iuasniuch a s a lecithin content in feces fat has been frequently denied3, while other authorities have maintained the reverse to be true‘, and have spoken of a high percentage amount of these bodies, i t appeared that further work in this direction was desirable. I n t h e following pages some observations on these and other points will be given. For our experiments the mixed feces from a number of men in normal health were collected, dried and extracted with absolute ether, after rubbing up with fine ignited quartz. I n the drying of feces in the ordinary way on the water-bath it is not possible to avoid the loss of some nitrogen, in non-protein combination, but the loss may be reduced somewhat by keeping the temperature low. On the other hand, the slow drying, with long contact with the air, occasions some change through oxidation processes. T h e loss of nitrogen from the fat-like bodies is t h e most serious of the objections to the water-bath method of drying, but in the working u p of large quantities of feces it is practically the only method available and was followed, therefore, in our work. By extraction in the Soxhlet apparatus we secured two lots of “fat” of about 40 grams each, which will be referred to as samples A and B. These crude fats were purified by solution in absolute ether, filtering and Presented a t the New York meeting of the Am. Chem. SOC.Dec. 3rst, 1906. Long, this Journal, 28, 704. Long and Johnson, this Journal, 28, 1499. it Hoppe-Seyler, Physiolosische Chemie, p. 337, Hoppe-Seyler, Chemische Analyse fur Aerzte, 6th Ed. p. 480. Bokay, 2. physiol. Chem.. 1, 157. 4 For example, Deucher, Maly’s Jahresber., 1898, p. 606. Also, F. Oefele, Maly’s, Jahresber., 1904,p. 457. 2
N A T U R E OF FECES FAT
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slow evaporation of the ether. There was a slight loss in this resolution in each case, possibly because the first extraction carried down traces of inorganic substances by aid of traces of water remaining in the dried feces. With the fat so secured, which was, of course, a mixture of all bodies present which u e soluble in absolute ether, the following tests were made. Many of these tests were carried out on the purified fat and also on a fraction precipitated fiom its ethereal solution by acetone. T h e results from the original fat will be given first. Experiments with Original Fat. Sample A was used for most of the tests, and B mainly for confirmation. T h e two lots of fat are not absolutely comparable, but practically so in most respects, since they were obtained from the feces of the same individuals, with an interval of a few weeks between t h e collections. Meeltiiig Point.-A constant melting point of such a mixture cannot be expected, from a consideration of the various factors which enter to modify i t . Some of the single fats present are soft, with a low melting point, which cholesterol and the related koprosterol, which are always present in relatively large amounts, have high melting points, the T h e lecithin-like first melting at 145’ and the second at about 96’. bodies have all a high melting point and when they are present the general consistence and behavior of the fat is greatly modified. I n our experiments with fat A the actual softening of the fat which could be designated as incipient fusion did not begin below about 65’, which value is higher than that usually quoted in the literature. T h e sample B showed even a higher fusion point, and not below i o o . T h e high melting point of crude feces fat depends not alone on the presence of cholesterol and other bodies mentioned above which may have their origin in the bile, but also on the nature of the fatty bodies of diet. When these fats are very hard with a high melting point their absorption is relatively imperfect and a considerable fraction may pass down the intestine to be lost with the feces, as was long since pointed out by Mueller’ who showed also that the feces fat may have a melting point of 85’ higher i n the mean, thau the melting point of the food fat. Phos$ho7 ZLS Coutent.--The recognition of the phosphorus in the crude fat is a very simple matter, but the determination of the compound or compounds in which it occurs present greater difficulties. T h e practical difficulty is greatly increased by the fact that different methods of extraction yield crude fats with very different phosphorus contents, and when these are considered in relation to the nitrogen contents found at the same time, no uniformity can be found, as a rule, as will appear in the remarks on nitrogen content, below. T h e many extractions we have made show that the amount of phosSee refercncein Schmidts und Strasburger, “Die Faeces des Menschen,” p. 149,
pliorus present in tile crude fats from t!ie feces of different individiials is exti-eixely variable, lict tlius fiir iio relation h a s 1 .ee:i found ccl1:iecti:i;: this axioiint i v i t h the diet or otiicr f;ictors. 111 ( , L I T enrlier paper:, rcferred to abovc, w e i i o t d i i i ,
