iQoS] HASSELBRING— ASSIMILATION OF PENICILI.IUM 177 



certain atomic groups. According to Xageli, carbon is assimilated 



O "^ -■.'T.v^^^i, 



trom the groups =-CH, and =CH, but in the latter case only when it 

 occurs in a chain of two or more C-atoms to which H is bound. Ben- 

 zoic acid is assimilated, but formic acid is not. On the other hand, 

 carbon is not assimilated when it is directly united only with O or N 



H 



similar 



group oxalic acid, urea 



sions 



Subsequent researches showed that the concl 

 were^ no longer tenable, since it was found that the molds were not 

 restricted to such specific groupings as he supposed. Reinke*' 

 greatly extended the list of substances which could be assimilated, 

 and showed that some of the particular groupings which Nageli 

 excepted could be utilized. Thus, for example, parabanic acid. 



/NH— CO 



co<; 



^NH— CO 



source 



carbon from urea and from formi 



be utilized bv this fundus 



M 



be established between the atomic structure of a substance and its 

 food value. The mechanism of assimilation probably differs with 

 each individual case and is as much dependent upon the nature of 

 the plant as upon the chemical reactions of the compounds used; for, 

 as already stated, everj' substance that has nutritive value for one 

 plant will not serve as a food for all plants. 



It was with a view of gaining, if possible, some knowledge of the 

 complex problem of the chemistry of the assimilation of some of the 

 smipler compounds that the work reported here was undertaken. 

 It was thought that by studying the effect of a number of related com- 

 pounds on the growth of the mold fungi, and noting the \^riations 

 caused by different stimulating agents, it would be possible to gain 

 some knowledge of the probable chemical reactions by which nutrient 

 substances combine with the constituents of the living celL 



This proved to be a most complex problem, whose solution is made 



^ Reinkie, J., Unters. Bot Lab, Gottingen. (Rev. in Bot. Zert. 4r:S5^- i^3» ^^ 

 Just's Bot. Jahresb. 11:55. 1883.) 



^ DiAKONOW, N. W., Orgaa^he Substanz als Xahrsubstanz. Bct. Deutsch. 

 Bot, GeseOs. 5:380-387. 1S87. 



