64 CARNEGIE INSTITUTION OF WASHINGTON. 



Some Aspects of Metabolism in the Fungi, by B. M. Duggar. 



Much valuable knowledge has been added to the literature bearing 

 upon the metabolism of the fungi. Nevertheless, the nutrition of 

 these organisms still offers a variety of problems which may throw 

 light upon the phenomena of metabolism in general, and may serve, 

 further, to indicate the causes of diversity or to relate these to condi- 

 tions of growth. 



For the most part the organisms which have been studied in the 

 past are the familiar saprophytic species of the laboratory, such as 

 Penicillium, Aspergillus, and Rhizopus, together wuth forms of techni- 

 cal and industrial interest, including the yeasts. In the study which 

 the writer has undertaken it is proposed ultimately to include forms 

 w^hich are diverse both in taxonomic relationship and in habitat or in 

 effects. So far the organisms employed have been chiefly those in- 

 ducing disease in plants or decay in timber, and they include 19 species 

 belonging to the following genera: Aspergillus, Botrytis, Fusarium, 

 Giber ella, Glomerella, Helminthosporium, Penicillium, Polyporus, Sclero- 

 tinia, and Sphceropsis. 



Following some experiments carried out during the preceding year 

 at the Missouri Botanical Garden, it seemed desirable at the outset to 

 simplify the media employed as far as possible, using relatively few 

 sources of carbon and nitrogen. As mineral constituents of the 

 nutrient solutions, there have been employed concentrations of mag- 

 nesium sulphate and potassium dihydrogen phosphate to give in the 

 cultures 0.02m and 0.05m, respectively. Ferric chloride has been used 

 to give a concentration of only 0.00004. As a source of carbon, 

 0.25m glucose or 11 per cent peptone has been employed, and either 

 potassium nitrate, ammonium nitrate, or peptone as a source of 

 nitrogen. The nitrates were used in a concentration of 0.2m, and the 

 peptone was made of such strength as to contain the same amount 

 of nitrogen in the concentration of potassium nitrate used. The cul- 

 tures were arranged in Erlenmxcyer flasks, and in the series here reported 

 they were grown at 58° F. and at 61° F. The amount of grow^th was 

 measured by the dry weight of the fungus mat. 



It is recognized, of course, that any form of carbon as a source of 

 energy must ultimately yield carbon dioxid, but it does not follow that 

 the course of metabolism, especially with relation to the by-products 

 produced, would be the same in all the organisms, nor would it be 

 necessarily the same under the influence of different sources of nitrogen. 

 In any case, it was desirable to determine, first of all, the relation of 

 the source of nitrogen to the growth of the various organisms employed. 

 The results so far achieved are referred to in this section of the report. 

 In the following section the changes in H-ion concentration will be 

 brieflj^ considered. 



