( 411 ) 



nitrogen, like the earbon, is fit ibi- assimilation l)y om- microbe. 

 Thong-li this qneslion has already partly been answered in the negative 

 by the preceding experiments, it should still be remarked iiere that in 

 nutrient liquids, without an expressly added nitrogen compound, for 

 instance in : 



Or still better in : 



without any further addition, a not inconsiderable grow tli of .Z>. r^Z/V/o»- 

 carhopldlus may occur, so that at least traces of an assimilable nitrogen 

 compound may be drawn from the air by this bacterium, whereas, 

 for the possibility of assimilation of the free atmospheric nitrogen 

 no indications w^ere found. 



We now turn to another question, which the assimilation of tlie 

 atmosplieric carbon gives rise to, namely: How great is the quantity 

 of the volatile substance wanted for the formation of the bacterial 

 lilni produced in our cultures ? This question is closely connected 

 with the following: How much of the compound is moreover consumed 

 b}' the resi)iration of our bacterium, escaping as free carbonic acid? 

 For answering these questions we have to measure the quantitv of 

 the carbonic acid corresponding with a determined weight of dry 

 bacterial substance, granted that the carbon |)ercentage of this sub- 

 stance be known. 



Our ex|)eriments relating to the measurement of the t{uantity of 

 carbonic acid i)roduced, are not yet closed, but as to tlie first [)art 

 of the question, we give the following calculation to fix the vobime 

 of air wanted for the i)roduction of the carbon, actually accu- 

 mulated in the bacterial tilms. We hereby make two chemical 

 suppositions which, to be sure, are fairly w^ell in accordance with 

 truth. First, we admit that the carbon, freed from tiie imkown 

 compound, as carbonic acid by a prolonged contact with alkali, 

 is consumed quantitalively by our bacterium and, secondly, that the 

 bulk of the bacterial cells consists of a subslance possessing nearly 

 the composition of cellulose ^). 



1) If accejjling Ihal the composition of the bacterial cells corresponds with 

 that of albuminous substances, then, instead of 44% tl., 52 to 55"/o G. should be 

 brought into account, and in this proportion the volume of the air should be 

 augmented. 



