NUTRITION OF FUNGI. .^83 



cular structure of their organised parts. But the Fungi, according to Naegeli, make 

 smaller demands than plants containing chlorophyll with respect to their choice of 

 mineral matters. They can exist provided three elements — viz., phosphorus, one 

 element of the series potassium, rubidium, and caesium, and, finally, one of the series 

 calcium, magnesium, barium or strontium — are supplied to them. Since, now, the 

 other elements here mentioned — viz., rubidium, ccesium, barium and strontium — 

 certainly do not occur at all places where Fungi grow, we may say they require phos- 

 phorus, potassium, and, in addition, calcium or magnesium. The difference between 

 them and normal plants lies in the latter needing calcium and magnesium at the 

 same time. Iron appears to be necessary only for the formation of the chlorophyll of 

 normal green plants, and is thus wanting in the Fungi ; and with respect to chlorine 

 and silica, which Naegeli reckons among the requirements for the nutrition of the 

 higher plants, the necessary facts have been already stated in Lecture XIV. The 

 essential difference between Fungi and the normal green plants, so far as the mineral 

 matters are concerned, would thus lie, according to Naegeli's researches, only in that 

 the Fungi do not need to take up magnesium and calcium at the same time, but 

 only require one of the two ; and that instead of this they can also make use of 

 barium and strontium, and, instead of potassium, of rubidium and caesium. These 

 are Naegeli's results concerning the elements necessary for the nutrition of Fungi. 



Since the Fungi are not able to decompose carbon dioxide and thus to produce 

 carbonaceous organic substance, because they lack chlorophyll, a carbonaceous 

 organic compound must be presented in the artificial nutrition of Fungi, in addition 

 to the compounds of the elements named above. According to all experience 

 hitherto, it appears that organic carbon compounds of the most various kinds can be 

 taken up by the Fungi, and then be employed for the formation of cellulose and pro- 

 toplasm by means of internal metabolism. Of special interest, however, for scientific 

 insight into the matter is the knowledge of those nutritive substances which are distin- 

 guished by their pecuHarly simple composition, and the other chemical properties of 

 which are so exactly known that definite conclusions may be drawn from them 

 respecting the chemical processes probably occurring in the nutrition of the Fungus. 

 In this sense Pasteur employed, so long ago as 1858, ammonium tartrate for the 

 artificial nourishment of the Mould-fungi, Yeast and Bacteria. For the nourishment of 

 Yeast-fungi, Naegeli distinguishes as well chosen a nutritive solution employed by 

 Adolf Mayer in 1869. I here subjoin the composition of this, in order to give the 

 reader a clear idea; but it is not therefore to be supposed that every nutritive 

 solution in which Yeast is to grow must have exactly this composition — it is simply 

 an example for illustration. The solution in question was as follows : — 



Water 100 Cu. cm. 



Sugar 15 grams. 



Ammonium Nitrate i 



Acid Potassium Phosphate .... o'5 „ 

 Tribasic Calcium Phosphate .... 0-05 

 Magnesium Sulphate o"2 5 



If then this nutritive mixture is a suitable one, a considerable multiplication of Yeast- 

 cells must be obtained in a short time, if a few of them have previou.s]y been placed 



