The President's Address. Btj H. J. Slack, 119 



and growth the presence of free oxygen, and the latter able to dis- 

 pense with it, provided they are brought in contact with a ferment- 

 able substance from which they can obtain the oxygen they need 

 by a process of decomposition — the latter, he affirms, to be ferments. 

 Septic vibrions he finds killed by free oxygen, and these come 

 under his designation of anaerohies. In other cases, and notably 

 in yeast plants, he notices a capability of living in either state ; 

 and in the last or anaerohic one, they act as ferments. 



Before proceeding further with M. Pasteur's researches, it will 

 be well to bear in mind what takes place in the life processes of the 

 higher chlorophyll-containing plants, and we shall then be able to 

 see what relation these aerohies and anaerohies bear to them. 



The experiments and observations of M. Corenwinder, extending 

 and confirming opinions expressed by M. Th. de Saussure, and 

 supported thirty years ago by M. Garreau,* show that the 

 respiratory process of plants is constant, and like that of animals 

 carried on by absorption of oxygen and exhalation of carbonic acid, 

 and that the absorption of carbonic acid with retention of carbon 

 and emission of oxygen is " a veritable digestion." The respiratory 

 acts belong to the nitrogenous matter of the plants, and the carbon 

 digestion to the chlorophyll, and it depends essentially upon the 

 influence of Hght, being most active during direct exposure to solar 

 rays and diminishing as the light is weakened. The carbou carried 

 oft' in the respiratory action comes from the supply obtained by the 

 digestive and assimilative processes. 



We learn from M. Pasteur that the moulds Penicillium and 

 Aspergillus, and the "mother of wine," Mycodermi vini, are 

 capable of living in either of the states named, and he describes a 

 variety of experiments showing these facts, and he remarks upon 

 them, " We are constrained to admit that the production of alcohol 

 and carbonic acid with the help of sugar, in a word, alcoholic fer- 

 mentation, are chemical acts connected with the plant life of cells of 

 very divers natures, and that they appear at the moment these cells 

 are no longer able to burn freely the materials of their nutrition by 

 the efiect of respiration, that is to say, by absorption of free oxygen, 

 and that they accomplish their life by utilizing oxygenated sub- 

 stances like sugar and combustible bodies, which give out heat in 

 their decomposition. The fennent character then presents itself 

 to us, not as pecuHar to this or that being, or this or that organ, 

 but as a general property of the living cell; a character always 

 ready to manifest itself, and actually doing so when its life is no 

 longer accomplished under the influence of free oxygen, or of a 

 quantity of that gas sufficient for all the acts of nutrition." f 



M. Pasteur gives drawings of the appearance of various cells 



* See ' Revue Sc!entifique,' Ibt August, 1874. 

 t 'LaBiere,' pp. 113, 114. 



