CONDITIONS OF LIFE OF THE BUDDING FUNGI. 519 



by Niigeli, and more especially by Hansen, are also more 

 free from objection because they have paid great attention 

 to the purity of the cultivations of the yeast.* 



As regards the nutrient materials required, the yeast Sources of 

 fungi agree very closely with the mould fungi, so that m 

 what was mentioned with regard to the latter applies 

 almost entirely to the former. A larger amount of 

 nitrogen is requisite for the yeast fungi in correspondence 

 with the larger quantity which they contain. The most 

 favourable source of nitrogen is the soluble and easily 

 diffusible albuminoid materials, and more especially 

 peptone ; but the place of the proteid substances may be 

 taken by ammoniacal salts, substituted ammonia, and 

 the other nitrogenous compounds mentioned in the case 

 of the mould fungi ; if, however, ammoniacal salts are 

 the only source of nitrogen the yeast cells appear to 

 undergo degeneration, their substance becoming richer 

 in fat and poorer in nitrogen ; and this degeneration 

 occurs still more readily if other conditions of life, such 

 as the presence of free oxygen, are also wanting (Niigeli). 

 Under circumstances otherwise equal peptone is about 

 four times better as a source of nitrogen than, for 

 example, tartrate of ammonia. With regard to the 

 nitrates there is an important difference between the 

 mould fungi and the yeast cells ; the nitrates are quite 

 unsuitable for the nutrition of the yeast, and cannot 

 serve as sources of nitrogen. 



Carbon has the same relation to yeast fungi as to Necessity of 

 mould fungi ; the best source is sugar, and then mannite, carbon - 

 glycerine, tartaric acid, &c. In the case of mycoderma 

 vim, alcohol appears to be an almost necessary nutrient 

 material, and can at most be replaced by malic acid 

 (Schultzf). With regard to the hydrogen, combined 

 oxygen, and sulphur there are no marked differences 



* Compare Pasteur, Ann. de Chim. ft de PIn/s., (3) vol. 58. Duclaux, 

 Theses present, a lafac. de sc. de Paris, 1865. Dubrunfaut, Compt. rend., 

 vol. 73. Schiitzenberger, Compt. rend., vol. 78. Mayer, Untersuchungen 

 iiber die alkoholltche Gahrung, &c., Vti/B&.Lcmdwirthgch. Versuchsstat.. 

 vol. 14. Mach, Anal, de Oenologie, vol. 4. Niigeli, Theorie der Giihrung, 

 1879. Untersuchungen iiber niedtre Pilze, 1882. Hansen, Meddedelser 

 fra Carlsberg Labornloriet : Kopenhagen, 18791884. 



f Cit. in Mayer, Gahrungschemie. 



