190 PHYSIOLOGY OF THE DOMESTIC ANIMALS. 



considerable nutritive value, since it contains still 16 or 18 per cent, of the 

 albuminous bodies and a small quantity of nutritive salts, and is readily 

 digestible in the alimentary canal. If meat is placed in water which is 

 already boiling the external surfaces are at once coagulated and but little 

 of the nutritive juices escape, so that, therefore, meat so prepared has a 

 greater nutritive value than meat which is placed in cold water and then 

 gradually subjected to boiling. The more rapidly, therefore, the exter- 

 nal surfaces of the meat are coagulated, as, for example, by roasting, the 

 greater will be the proportion of nutritive substances retained. In roast- 

 ing the haemoglobin of the blood becomes decomposed, and the meat 

 then takes the characteristic brown color of roast meat, while at the same 

 time a number of aromatic substances, to which the peculiar .odor and 

 taste of roast meat are due, are developed. By soaking meat in brine 

 putrefaction is prevented, but meat so salted loses a certain degree of 

 nutritive value from the fact that a considerable quantity of albuminous 

 bodies and extractive matters and salts pass into the pickling solution. 

 Smoked beef is protected from decomposition by the development of 

 phenol in the smoke ; this substance is an energetic preventive of decom- 

 position. Beef so dried preserves nearly all of its nutritive principles, 

 only having lost in water. Meat-broth obtained by boiling meat with 

 water has usually an acid reaction, from the lactic acid of meat, and con- 

 tains a greater part of salts and extractive matters of meat, together 

 with a certain amount of gelatinous albuminoids and a small amount of 

 fat. Meat-broth will contain about 1.4 per cent, of solids, but is of slight 

 nutritive value, since it contains scarcely any albuminoids or carbo- 

 hydrates, and but an extremely small amount of fats. It consists almost 

 solely of the extractive matters and salts, and is, therefore, simply of 

 value as a means of supplying the inorganic salts of meat. From the 

 extractive matters and the potassium salts present it is to a certain ex- 

 tent a stimulant, since it simply in this way produces a greater secretion 

 of digestive juices. Beef-tea, prepared by putting meat in cold water 

 and gradually raising the temperature, has a higher nutritive value than 

 the commercial beef extracts from the fact that the soluble albuminoids 

 have time to pass into solution in the water before their temperature of 

 coagulation has been reached. The composition of meat will be given 

 in greater extent under the subject of Muscles. 



Eggs, especially those of the hen, are also valuable nutritive articles, 

 containing also examples of all the different food-stuffs ; thus, one hun- 

 dred parts of egg, the shells having been removed, consist of 73.9 per 

 cent, water and 26.1 per cent, solids. Of the latter 14 per cent, is 

 albuminoid, 10.8 per cent, fat, a small amount of sugar, and 1 per cent, 

 of inorganic salts, especially sodium chloride, potassium phosphate, and 

 a small amount of- oxide of iron. 



