EGGS. 423 



(fat cheese), by means of rennet, permitting the whey to run off and well salting 

 the coagulated mass. After some time the cheese ripens, the casein, probably 

 with the formation of sodium albuminate, becoming soluble in water once more. 

 In some kinds of cheese liquefaction occurs, with the formation of peptone and 

 diastatic ferment as a result of the action of the cheese-spirillum (spirillum 

 tyrogenum). On further decomposition, leucin and tyrosin appear. The amount 

 of fat in the cheese increases, while that of casein diminishes. Later on, the fats 

 decompose; the volatile fatty acids yield the characteristic odor. The formation 

 of peptone, leucin, and tyrosin and the splitting up of the fats suggest the 

 digestive processes. Cheese contains also saprophytic microbes. 



EGGS. 



Eggs also must be looked upon as a complete food, as the organism 

 of the young bird is capable of developing from them. The yolk contains, 

 as the characteristic albuminous body, vitellin; also an albuminate in the 

 capsules of the yellow yolk-globules, the egg-casein, which is precipitated 

 by means of a one per cent, solution of sodium chlorid, on combining 

 with oxygen; nuclein from the white yolk; fats in the yellow yolk 

 (palmitin and olein) ; cholesterin, much lecithin, and, as a product of 

 decomposition, glycerophosphoric acid, grape-sugar; pigments (lutein), 

 including one containing iron and related to hemoglobin; finally salts, 

 qualitatively as in the blood, quantitatively as in the blood-corpuscles; 

 gases. 



The white of the egg contains egg-albumin as the principal con- 

 stituent, in addition to some globulin, mucin-matter and albumose, also 

 small amounts of palmitin and olein, partly saponified by sodium; grape- 

 sugar ; extractives ; finally salts that resemble qualitatively those of the 

 blood and quantitatively those of the serum. There are, besides, traces 

 of fluorin. On a diet of eggs and also on a diet of roast meat, relatively 

 more of the nitrogenous constituents are absorbed than of the fats. 



MEAT AND MEAT-PREPARATIONS. 



In the form in which it is consumed, meat contains, in addition to 

 the proper muscular tissue, an admixture in greater or lesser amount of 

 the elements of fatty, connective and elastic tissues. Beef freed from fat 

 and dried contains, according to Argutinsky, carbon 49.6, nitrogen 15.3, 

 hydrogen 6.9, ash 5.2, oxygen and sulphur 23 per cent. According to H. 

 Schulz the amount of sulphur present is i.i per cent, of the dried muscle. 

 The chemistry of muscle is fully discussed on p. 548. The proteids of 

 muscle are contained in the contractile substance and in part in the 

 saturating fluid. The fats are derived for the greater part from the 

 inter-fibrillary fat-cells, the lecithin and cholesterin chiefly from the 

 muscle-nerves. The gelatin-yielding substance is supplied by the con- 

 nective-tissue fibers of theperimysium, the perineurium, the vessel- walls 

 and the tendinous parts. The red coloring-matter, which is present in 

 varying amount even in the muscles of the same animal (red muscles 

 and white muscles), is hemoglobin. In addition, some muscles, for 

 example the heart, contain the related substance, myohematin. Elastin 

 is present in the sarcolemma, the neurilemma and the elastic fibers of 

 the perimysium and the vessel- walls. Keratin, in small amount, is de- 

 rived from the endothelium of the vessels. The following are to be con- 

 sidered as end-products of the retrogressive metamorphosis of the muscle- 

 substance proper, in which also they occur in greatest amount: k;reatin 



