June 15, 1900.] 



SCIENCE. 



931 



know that cells produce heat by the process 

 of respiration (some of the lowest forms of 

 fungi also by fermentative action) and that 

 this heat energy is necessary for carrying 

 on the various functions of life, for which 

 purpose it can be transformed into chem- 

 ical, electrical and mechanical energy in the 

 cells. But how are the cells enabled to 

 bring on the active oxidation phenomena 

 that characterize the respiration process, 

 and by what special contrivance can the 

 heat energy thereby produced be converted 

 into other forms of energy ? 



The conception of the nature of living 

 protoplasm has changed with the progress 

 of time. Formerly and by some authors 

 even at the present time, it was defined as 

 a changing mixture of diiferent substances 

 and all compounds found in the protoplasm 

 were considered indispensable and intrinsic 

 parts of it. Compare for instance, the pub- 

 lications of Reinke on the protoplasm of 

 JEthalium septicum. Recently also Verworn 

 has returned to this old conception. 



But such a view cannot be logically en- 

 tertained when we see that a certain pro- 

 toplasm does continuously the same kind 

 of work like a mechanism of a fixed struc- 

 ture. This mechanism consists here in a 

 specific structure built up of easily change- 

 able proteins requiring a certain amount of 

 water and mineral salts. The amount of 

 imbedded material, however, may continu- 

 ously change. This material consists either 

 of thermogens, as fat and sugar, or of mere 

 by-products of metabolism which are soon 

 excreted after their formation, either to the 

 outside or into the vacuole. 



What kind of work will result? it depends 

 upon the configuration* and the specific 

 chemical structure of these protein mole- 

 cules on the one hand, and upon the specific 

 construction of the machinery on the other. 

 Thus, the protoplasts of the various vege- 

 table and animal glands resemble just as 



* The relative position of atoms in space. 



many different chemical laboratories ; the 

 protoplasm of the muscular fibers severs 

 molar motions ; that of the nerves is es- 

 pecially adapted to conduct impressions by 

 irritation to considerable distances. But 

 the most complicated differentiation governs 

 the structures of the nuclei of the genera- 

 tive cells, the most intricate laws rule the 

 genetic differentiations in the development 

 of an organism.* 



From the chemical standpoint our first 

 inquiry is directed, as alreadj' mentioned, 

 to the question : What causes the respiration- 

 process of the cells f What enables the pro- 

 teins to cause the active oxidations of fat 

 and glucose as long as the cells are alive, 

 and why do these oxidations cease as soon 

 as the cells are killed? Oxidation is a 

 purely chemical phenomenon ; hence, this 

 question is of a plain chemical nature. Some 

 might claim that by the death of the cells 

 the organization is destroyed and this is the 

 cause of the stoppage of the oxidation. But 

 this view cannot be upheld, since even the 

 most complicated machinery cannot pro- 

 duce work without the impelling energy. 

 There must also be a certain amount of 

 energy at the bottom of the respiration 

 itself, there must be some energy for kind- 

 ling the fire of the locomotive. What is 

 this energy that leads to respiration? 

 There remains no other answer than this : 

 It is chemical energy caused by the specific nature 

 of the proteids of the living protoplasm which 

 nature changes in the process of dying. ^ Nu- 



* Nuoleo proteids form the framework of the nu- 

 cleus and of the cytoplasm and may exist in innumer- 

 able isomeric forms, of which the stereo-isomerio 

 forms probably are of great importance as regards the 

 differences between species. The word proieid is used 

 here to designate the complicated compounds of pro- 

 teins, such as nucleins, haemoglobin, mucin, while the 

 word protein comprises all kinds of albuminous matter 

 in a general sense. 



t A chemical change in the proteins of the living 

 matter in the dying process was assumed as early as 

 1837 by John Fletcher and again in 1875 by E. 

 Pfliiger. But even at the present day many physi- 



