403 LECTURE XXV. 



of alcohol under the circumstances named in the higher plants has never yet been 

 quantitively determined, emphasis must be laid on the fact that wherever alcoholic 

 fermentation has been observed in the absence of oxygen (of course apart from 

 the Ferment-fungi) objects have been exposed which have not merely undergone 

 intra-molecular respiration for 1-2 hours, but have been cut off from the access 

 of atmospheric oxygen for days or weeks. Now Wortmann shows (though he 

 himself inclines to Pfeffer's view), that after the first few hours the intra-molecular 

 respiration already indicates an abnormal condition of the plant, whence 1 draw the 

 conclusion (to which Naegeli and Borodin had already ajiTived in another way), that 

 the formation of alcohol in the absence of oxygen is an abnormal process throughout, 

 and has nothing to do with ordinary respiration. 



The most important fact, however, and one which must never be lost sight of in 

 comparing intra-molecular and normal respiration, lies in that intra-molecular 

 respiration cannot provide the forces necessary for gi-owth and the motility of irritable 

 organs. So long as the access of external oxygen is excluded, the plants are im- 

 movable, rigid, and growth comes to a standstill : a point to which Wortmann has 

 already referred at the conclusion of his excellent work. 



The true meaning of respiration, however, still remains unexplained. Never- 

 theless, so much is established, that it is a function of active living protoplasm. 

 Since although it results from Boussingault's investigations that carbo-hydrates only 

 are consumed in normal respiration, this takes place on the other hand only when 

 they are exposed to the influence of living protoplasm. And that it is not in any 

 way the proteid substances, regarded as chemical compounds, which maintain the 

 respiratory process, results directly from the fact that in non-organised proteid 

 substances neither normal nor intra-molecular respiration is to be observed. Dormant 

 protoplasm never respires. It is, on the contrary, a property of active and living 

 protoplasm to respire; or, perhaps better, the respiratory process is the first and 

 most fundamental expression of the vital processes in protoplasm. The substance 

 of what intra-molecular respiration teaches, according to the facts established by 

 Wortmann, is that it is not the oxygen penetrating from without which gives the 

 first impulse to the chemical changes of respiration ; but that primarily, and in the 

 protoplasm in the first place, a decomposition of the molecules of the proteids 

 occurs, which terminates with the formation of carbon dioxide ; that, however, by 

 means of the entrance of oxygen from without a restitutio in integrum takes place, 

 when a carbo-hydrate, and especially sugar, is consumed. 



Thpse are, moreover, only preliminary attempts to obtain an insight into the 

 proces^of respiration. It is certain that numerous patient and laborious investiga- 

 tions will yet be necessary ere we attain complete clearness as to these matters. 



While hitherto the evolution of carbon dioxide, and (as we are warranted in 

 assuming from Boussingault's researches) the formation of water from the organic 

 substance, have been placed in the foreground as expressing the activity of respiration, 

 only the terminal result of the process is intended to be thus characterised. That 

 a long series of chemical processes in addition are first induced in the plant by 

 respiration, on which the whole vital process finally depends, there can be no doubt 

 whatever. We may perhaps regard the formation of those acids which abound 

 ill oxygen at the commencement of germination, and likewise in shooting buds, as 



