^78 BOTANICAL GAZETTE [march 



more 



anisms can be subjected. Although no finally 



factory conclusions 



been worked out with great care. As I am for the present compelled 



by circumstances to discontinue the work, it is desirable to present 



sible significance. 



final remarks on their pos 



METHODS 



The form selected for this work was a strain" of Penicillium glau- 



cum. A number 



they did not thrive well under the conditions of the experiments. 

 Penicillium, which has been used in innumerable physiological inves- 

 tigations, is especially suitable for this work on account of its omnivo- 

 rous habit, and because many compounds have been studied with 

 regard to their nutritive ralue for this fungus. The same strain of 

 the mold was used throughout. The stock-cultures were always 

 grown on sterilized bean-stems, so as to avoid any possible temporar>' 

 influence of the substratum on the strain. 

 ^ The culture medium used was a solution of the necessary inorganic 



purest grades obtainable in the market. Except where 



specially noted, the 



in the same concentration, namely is™ NH 



and 0.25^- MgSO,, per 100-. Potassium 



mm 



magnesium 



varied 



^ uLuers. 1 nese changes are noted in the respective tables. It ^v-as 

 the purpose in this work to have the mineral solution alike in aU the 

 c^tures in order to make the different series exactly comparable. 

 Jhis was carried out, except where special problems occurred which 

 demanded a change from the standard. 



^ a source of carbon the foUowmg substances were used: alcohol 

 L.H.OH), potassium ethyl sulfate (C.H^KSO,), ethyl nitrate 

 J^^jf ^3), ethyl acetate (CH3COOC,H5), potassium acetate 

 (CH COOK), and acetic acid (CH3COOH). These compounds 

 are aU closely related, and have certain radicles in common. The 

 combination of those radicles with various groups has a definite 

 e ect upon the mode of reaction of the compounds. By a compara- 

 i^e study of a large number of compounds of this nature with regard 



