354 DIVISION III. MODE OF LIFE OF THE FUNGI. 



they can only take up their food in a fluid or gaseous condition. The general 

 difference between the process of nutrition in the Fungi and in plants which contain 

 chlorophyll and similar substances consists in their inability from want of chloro- 

 phyll to decompose carbon dioxide. They must obtain their carbon by taking 

 up organic carbon-compounds previously formed in some other bodies, as is the 

 case with all organisms or parts of organisms which do not contain chlorophyll. 



According to experiments with Moulds and Saccharomycetes in artificial nutrient 

 solutions, the nitrogen is taken up and disposed of to the benefit of the plant in the 

 form of inorganic compounds, provided the carbon is obtained as some organic 

 compound such as sugar ; Moulds like Penicillium, Mucor racemosus, and Aspergillus 

 niger (Pasteur, Fitz, Raulin) take up nitrogen from ammonia-compounds as well as 

 from nitrates, while ammonia is a good and nitric-acid a very indifferent source of 

 nitrogen for the Yeast-saccharomycetes (Mayer, Nageli) 1 . Moreover the need 

 of carbon as well as that of nitrogen may be supplied in the same Fungi by means of 

 organic compounds which they are able to take up ; some of these supply more 

 nutrition than others, and some supply none at all. According to Nageli almost all 

 compounds of carbon afford nourishment with the addition of oxygen, provided they 

 are soluble in water and not too poisonous. Urea, formic acid, oxalic acid and oxamide 

 (Nageli) besides CO 2 and cyanogen are exceptions to this rule. A large number 

 of compounds may serve as sources of nitrogen, if they are in a soluble state or can 

 be made soluble by the Fungus. Free nitrogen and cyanogen cannot by themselves 

 supply nourishment. Some compounds containing nitrogen may serve at the same 

 time as sources of nitrogen and of carbon, others, as oxamide and urea, only as 

 sources of nitrogen. According to Nageli, Penicillium grows best in a solution of 

 proteid (peptone) and sugar ; then in the following solutions arranged in descending 

 order according to their nutritive capabilities: i. leucine and sugar; 2. ammonium 

 tartrate or sal-ammoniac and sugar; 3. proteid (peptone); 4. leucine; 5. ammonium 

 tartrate, ammonium succinate, asparagin ; 6. ammonium acetate. 



As regards the constituents of the ash the requirements of the Fungi are 

 essentially the same as those of other plants, but with this limitation according 

 to Nageli 2 , that Fungi are comparatively less particular in their selection. 



The amount of available food-material in the substratum is not the only point of 

 importance ; its chemical nature also has to be considered, as was intimated 

 above in the account of the conditions required for germination. Dutrochet s 

 discovered some time since that the development of Moulds was affected by the acid 

 or alkaline reaction of the fluids in which they grew, and more recent investiga- 

 tions, dating from the year 1860, have shown the existence of important specific 

 differences in this respect in the Fungi. The common Moulds flourish in nutrient 

 solutions which are more or less acid ; they do not grow so well or refuse to grow 

 in neutral or slightly alkaline fluids. The Schizomycetes behave as a rule in the 

 reverse way (vid. infra, Chap. XI). A trace of acid is sufficient to retard the develop- 



1 A review of the subject and its literature will be found in Pfeffer, Physiol. I, 242. See also 

 Nageli, Ernahrung d. niederen Pilze (.Untersuch. &c. 1882, I, and Sitzgsber. d. MUnchener Acad. 

 Jnli, 1879), and Raulin in Ann. d. sc. nat. ser. 5, XI (1869), 220. 



: Untersuchungen, i88a. 8 Ann. d. sc. nat. ser. 2. I. p. 30. 



