49 



served can also be accounted for by attributinij thoni to certain dif- 

 ferences in the atmospheric conditions. 



(6) The more considerable absorption of oxys^en by seeds under 

 the influence of li^iht explains the fact that asparagine (the medium 

 for the conveyance of the reserved albuminous substances in the ger- 

 mination of leguminous plants) only disappears in plants exposed 

 to the light and continues present in those raised in the dark. The 

 comj^arative researches of Pfeller (1ST2) upon the chemical com- 

 position of asparagine ajid other substances showed that asparagine 

 is poorer in carbon and in hydrogen and richer in oxygen than 

 legumine and other albuminoids. The transformation of leguniine 

 into asi:)aragine is accompanied by the absorption of a certain quan- 

 tity of oxygen. On the other hand, it is effected only by the influ- 

 ence of light, the reason being that light increases the quantity of 

 oxygen absorbed, and therefore exerts only an indirect influence on 

 this change, as had already been surmised even when we were not 

 acquainted with the reasons. 



(7) Other new and important conclusions become apparent from 

 these experiments and those which follow, and although they have 

 no direct connection with the subject of my work I think it will be 

 well to designate them briefly. 



The quantity of ox^'gen aljsorbed in a certain space of time by a 

 seed in process of germination varies very considerably according to 

 the temperature; it increases with it, as has been alreadj^ proved in 

 treating of the respiration of i^lants in the dark. The general results 

 of mv experiments, and particularly of Nos. 9 and 10, leave no doubt 

 of this fact. We can therefore easily understand what errors haA'e 

 been committed by those experimentalists who have given calcula- 

 tions of this absorption of oxygen by certain seeds without taking 

 into consideration the conditions as to temperature. Their figures 

 have no value whatever, particularly in vicAv of a fact stated by me 

 several times alread}^ viz, that the quantity of oxygen absorbed by a 

 seed is not at all in proportion to its apparent development, but, on 

 the contrary, undergoes considerable variation, depending upon the 

 influence of the external agents affecting the phenomenon. x\ccord 

 ing to my observations, this quantity may vary as two to one, or even 

 more, in two plants of identically the same weight, but placed in dif- 

 ferent thermic conditions from the commencement of their germina- 

 tion to the emerging of the rootlet. From this point of view, then, 

 the plant acts like a complete organism, its respiratory action being- 

 accelerated or retarded always, however, within physiological limits, 

 like those of an animal under the influence of certain exterior changes. 



Having thus shown that germinating seeds absorb more oxygen in 

 the light than in darkness, Pauchon conducted some experiments to 

 determine the ratio betw^een the oxygen and the carbonic acid, and 

 draws the following conclusions (see page 182 of his work) : 



Experiments Nos. 3 and 4 have a real value for the solution of the 

 problem brought forward in this part of my work. As to the partial 

 results given by experiments Xos. 1, 2, and 5, their accuracy can not 

 be doubted; therefore I shall make use of them as confirmatory docu- 

 ments. I must repeat that the numbers used for the proportions of 

 2667—05 M 4 



