( 410 ) 



Distilled water 100 



K.HPO, 0.02 



(NH,), SO, 0.02 



Na.CO, 0.1 



"Mineral solution" J drop 

 after 7 months (5 May — 1 Dec.) 155 mgrs. of permanganate, corre- 

 sponding with ca. 300 mgrs. of dry bacterial substance per litre, 

 which production is less than that, obtained in other cases under 

 tlie same cii-cumstances but without carbonate, so that here also, 

 the action of the carbonate, the long time of cultivation being taken 

 into consideration, was not faxorable. Quantities of carbonate, 

 smaller than 0.1 "/„, were neither successful. 



The results of this examination can be thus summarised, that for 

 the growth of B. oligocarboplilhis an atmospheric carbon compound 

 is actually consumed, but that this cannot possibly be free carbonic 

 acid. Furthermore, that also combined carbonic acid cannot serve 

 for its nutrition. 



7. Nature of the assimilated atmospukkic carbon compound. 



If the carbonic acid of the air cannot be the food of B. o/tf/o- 

 carhophUus, what other atmospheric carbon source might then come 

 into consideration? 



It is clear, that we should I hink iiere of tlie carbon-containing 

 component of the air, discovered in 1862 by the botanist Hermann 

 Karsten ^), and recently discovered anew by French experimenters, 

 especially by Mr. Henriet "'). It is true that the chemical nature of 

 this substance has been hitherto unknown '), but yet it is certain that 

 we ha\e hei'e to do with an easily oxidisable compound (or com- 

 pounds), for a prolonged contact with alkali and air will already 

 suffice to split oif carbonic acid from it. Furthermore, according 

 to the statement of the French investigator, the substance probably 

 contains nitrogen. 



This latter circumstance gives rise to the question Avhether this 



1) H. Karsten. Zur Kenntniss des Verwesungsprocesses. Poggendorff's Annalen 

 Bd. 191, pag. o43. 1862. To this place, as also to the not unimportant older literature 

 on the carbon compound of the air, my attention was drawn by Mr. G. van Iterson. 



-) Gompies Rendus T. 135, pag. 89 et 101. 1902. 



^) Henriet thinks that the substance must be a monosubstituted formamid with 

 the formula HGO.NHR, where R represents a still unknown alkylrest. But then it 

 is not easy to understand, why the production of carbonic acid takes place so 

 readily. It might then rather be expected that, with an alkali a forraiate would 

 result and no carbonate. 



