i LIVING MATTEE 35 



place iii the tissues or fluids, accompanied by a similar cleavage of 

 fats and carbohydrates. 



The phenomena of post-mortem autolysis have been the subject 

 of numerous recent researches, in the hope of throwing some light 

 upon intra vitam, intracellular, fermentative processes, which 

 we must assume to be of great importance in the metabolism of 

 the tissues and of the living cells. The results so far obtained 

 are not, however, decisive enough to serve as the basis of any 

 definite conclusion. 



XI. The proteins of living matter are always accompanied by 

 a large amount of simpler substances, nitrogenous or non- 

 nitrogenous, which represent products of decomposition or of 

 retrogressive changes in these substances, or in nutrient substances 

 from outside, which have been more or less elaborated by the 

 activity of the cell. The name deutoplasm has been given to 

 these substances as a whole, that of cytoplasm being reserved for 

 the living substance generically known as protoplasm. 



The nitrogenous products of the retrogressive metamorphoses 

 of protein form a series of well-defined chemical substances, many 

 of which are eliminated with the urine in very varying amounts 

 in the higher animals. The largest in quantity and in nitrogen 

 content is urea, next come uric acid, hippuric acid, creatine and 

 creatinine. The purine bases form a distinct group already referred 

 to, xanthiue, hypoxanthiue or sarkine, adenine, guanine, and they 

 are the decomposition products of nuclein. These substances 

 cannot all be extracted from the tissues, owing to the minimal 

 quantity in which they are present. Another group of nitrogenous 

 and phosphorised substances, the lecithins, occur, according to 

 Hoppe-Seyler, in every plant and animal cell, and in particularly 

 large quantities in the elements of nerve, the blood corpuscles and 

 in yolk of egg. In its chemical characters (solubility in ether and 

 alcohol, insolubility in water) lecithin shows great similarity to 

 fats. It resembles nuclein inasmuch as it contains phosphorus, 

 and is capable of forming unstable combinations with albumin and 

 other substances. The yolk of egg contains a combination of 

 lecithin with vitellin. Protagon, extracted by Liebreich (1865) from 

 the brain, is the combination of a lecithin with cerebrin, a nitrogen- 

 ous substance free from phosphorus, similar to the glucosides. 



The non-nitrogenous organic products which enter into the 

 chemical constitution of the cell are represented by the fats and 

 carbohydrates. These originate partly in the consumption of 

 proteins, partly from external food-stuffs, or their transformations 

 as effected by the cell-enzymes. 



Chemically considered, the fats represent combinations of 

 glycerin (triatomic alcohol) with the acids of the fatty series 

 (stearic, palmitic, butyric, valerianic, caproic), as also with oleic 

 acid, which does not belong to the normal fatty series. 



