LIFE WITHOUT OXYGEN 119 



relationship between anaerobic and aerobic respiration ; that 

 complete aerobiosis represents an evolution from complete 

 anaerobiosis ; further, that in all probability the middle forms 

 of this evolution may be discovered. 



Such a conclusion has already been foreshadowed in the 

 preceding section ; the idea was first put forward in tentative 

 fashion by Pfeffer 1 as far back as 1878 but rather hesitatingly 

 sustained in his further researches published in 1884-5. 2 

 Pfeffer's facts, however, did not seem entirely conclusive even 

 to him ; and it remained for Godlewski, Palladin and their 

 followers to establish this relationship on a firm experimental 

 basis. Part of this work has already been noted ; the main facts 

 which speak for the conclusion may be summed up as follows : 



1. That between the forms which are strictly anaerobic and 

 those which are strictly aerobic there are countless forms which 

 are more or less indifferently one or the other. 



2. That this latent capacity may apparently be developed 

 in a wide number of forms which naturally appear to be deci- 

 sively one or the other — that is, may be "adapted" to the one 

 form of life or the other, by passage through a suitable number 

 of cultures. 



3. That aerobic respiration appears to be simply a height- 

 ened form of anaerobic respiration, carrying the chemical 

 process one step further and ordinarily at a much more 

 rapid rate. 



4. That many life processes, as for example the germination 

 of seeds, may be carried a certain distance in the absence of 

 oxygen ; they then come to a stop but the processes are 

 resumed when either oxygen or an easily oxidisable substance 

 like sugar is supplied. 



5. That the establishment of the essential part played by 

 oxygen alike in the plant and animal economy, viz. that of 

 a waste remover, makes clear the natural relations of these 

 two forms of respiration and the nature of the " evolution" from 

 one form to the other. 



6. That the need of oxygen is apparently directly related 

 to the combustion or " metabolism" of fats and carbohydrates; 

 that both of these processes are a function of temperature 

 and that as temperature decreases the need of oxygen sinks 

 rapidly, so that at very low temperatures (under io° C.) 

 metabolism is largely, if not exclusively of protein, i.e. 

 anaerobic. 



7. That the processes of fermentation are identical with 



1 W. Pfeffer, Landw. Jahrb. 8o5, 11, 1878. 



* Unters. a.d. hot. Inst, su Tubingen, 105, 1, 1884-5. 



