CHEMICAL RELATIONS OF PROTOPLASM. 83 



tegrates, and wastes away, giving oft' as waste matter tlie various 

 clieniical products of the combustion, and lil)eratin<r eneri^v as 

 lieat and meclianical work. Tlie loss of substance is, liowever 

 continually made good (much as the coal is replenished) 1)V the 

 absorption of new substance in the form of food, wliifli mav 

 consist of actual protoplasm, derived from other living bein<'-s, 

 or of substances convertible into it. These substances are in 

 some unexplained way converted into protu])lasni and tlius 

 built into the living fabric. 



To this dual process of waste (" /I'rt?^*^^^*??/.") and repair 

 {'''• anahoUsm^^) is applied the term metaholism^ which must be 

 considered as the most characteristic and fundamental propertv 

 of living matter. It is evident from the foregoing that meta- 

 bolism involves on the one hand a destructive action {katahol- 

 isiix) through whicli protoplasm disintegrates and energy is set 

 free, and on the other hand a constructive action (anaholinn) 

 whereby new proto23lasm is built up from the income of food and 

 fresh energy is stored. It is a most remarkable fact that as far 

 as known the constructive action resulting in the formation of 

 new protoplasm never takes place except through the inmiediate 

 agency of protoplasm already existing. In otlier words, there is 

 no evidence that "spontaneous generation" or the production 

 of living from lifeless matter without the intluence of antecedent 

 life ever takes place. Nor is there any evidence that any energy 

 can be "generated," but rather that the vital energy of living 

 things is only the transformed energy of their food, and that 

 "vital force" having an origin elsewhere than in such energy 

 does not exist. 



Chemical Relations. We know nothing of the precise chemi- 

 cal composition of living protoplasm, because, as has been said 

 (p. 2), living protoplasm cannot be subjected to chemical analy- 

 sis without destroying its life. But the results of chemical ex- 

 aminations leave no doubt that the molecules of protoplasm are 

 highly complex and are probably separated from one anotlier by 

 layers of water. 



A. Proteids. It has already been stated (}>. 3) that tlie 

 characteristic products of the analysis of protoplasm are the 

 group of closely -related substances known sls proteids. But pre^- 

 teids form only a small part of the total weight of any plant or 



