December 12, 1902.] 



SCIENCE. 



931 



purely inorganic matter reveals an unex- 

 pected constructive power in some forms of 

 vegetable protoplasm. The question of the 

 energy made use of in proteid construction 

 is in an equally unsatisfactory condition. 

 Laurent, Marchal and Carpiaux have 

 stated that the rays of the violet and ultra- 

 violet region of the spectrum are absorbed 

 and devoted principally to the construction 

 of nitrogen compounds from the nitrates, 

 or the compounds of ammonia, which are 

 absorbed by the plant, while the interven- 

 tion of the chlorophyll apparatus is un- 

 necessary for this purpose. The experi- 

 ments which they give in considerable de- 

 tail upon this absorption carry much weight 

 and appear conclusive. Unfortunately 

 other observers have failed to confirm them, 

 so that at present the matter must be left 

 open. 



Among the problems connected with the 

 nutrition of the plant, the part played by 

 alcohol has recently come into prominence. 

 Alcohol was originally associated only with 

 the lower fungi, and especially with the 

 yeast plant. Biological problems of grave 

 importance arose in connection with the 

 Saccharomyces, apart from what seemed at 

 first the larger question, viz., the nature 

 of fermentation. A prolonged study of 

 the latter phenomenon led Pasteur to the 

 view that alcoholic fermentation is only the 

 expression of the partial asphyxiation of 

 the yeast, and its efforts to obtain oxygen 

 by the decomposition of the sugar. It is 

 hardly necessary here to remind you of the 

 controversies that centered about the ques- 

 tion of fermentation and the theories held 

 and abandoned as to its cause. The 

 biological phenomena have, however, a 

 claim now upon our attention in the light 

 of some very remarkable researches that 

 are calling for our attention and criticism 

 to-day. Pasteur's explanation of the be- 

 havior of the yeast was, as we have seen, 

 such as to connect it with the respiration 



of the plant. AVhen oxygen was withheld 

 from active yeast sixty to eighty parts of 

 sugar disappeared for one part of yeast 

 formed. When oxygen was present not 

 more than ten parts of sugar were decom- 

 posed for the same amount of yeast produc- 

 tion. Undoubtedly the stimulus of as- 

 phyxiation materially stimulated the yeast 

 metabolism. 



But certain observations did not agree 

 with Pasteur's explanation. An energetic 

 fermentation takes place in the presence of 

 oxygen, the plant multiplies extremely 

 quickly, and its metabolism appears very 

 active. Schiitzenberger argued against 

 Pasteur's explanation with some force, em- 

 phasizing these points of disagreement be- 

 tween his hypothesis and the facts, and 

 claimed that the matter rather concerned 

 nutrition than respiration. He based his 

 view on experiments carried out to ascer- 

 tain how respiration was affected under 

 changed conditions. 



The results he obtained were briefly the 

 following : 



1. In a watery liquid without sugar, but 

 containing oxygen in solution, the quantity 

 of oxygen absorbed in unit time by a 

 gram of yeast is constant, whatever pro- 

 portion of oxygen is present. 



2. In a saccharine liquid containing al- 

 buminous matter as well as sugar, and with 

 oxygen in solution, the same result is ob- 

 tained, except that the quantity absorbed 

 in unit time is greater. 



3. In two digestions carried on side by 

 side for some time, one being supplied con- 

 tinuously with oxygen and the other de- 

 prived of it, the former produced most 

 alcohol. 



If the decomposition of the sugar had 

 been the result of the respiratory activity 

 of the yeast cells at the expense of the com- 

 bined oxygen of the sugar, it would seem 

 that fermentation should either not have 

 taken place at all in the presence of free 



