550 



VITAL ACTIONS OF THE LOWER FUNGI. 



Absence of 

 nitrogenotis 

 excrementi- 

 tious mate- 

 rials. 



products of the decomposition of the proteid materials. 

 In the same manner amides, such as leucine and tyrosin, 

 also guanine, xanthine, and sarcine, are found in the yeast 

 and fission fungi. More especially in the so-called self- 

 fermentation of the yeast numerous combinations of this 

 kind occur, while asparagine and glutamine have not as 

 yet heen demonstrated in "the lower fungi. 



These amido bodies are for the most part good nutrient 

 substances; there is no doubt that in the case of the 

 lower fungi the necessary nitrogen can be obtained from 

 them alone, and that they suffice for building up the 

 proteid material of the protoplasm ; while, on the other 

 hand, where the nutriment is exclusively albuminous, or 

 in the self-fermentation of the yeast, it has been shown 

 that they arise from the splitting up of proteid-like 

 bodies. These serve at the same time as plastic material 

 and as excreta ; and it is typical of the economical manner 

 in which as regards nitrogen the functions of the fungi are 

 performed, that in the decomposition of these substances 

 portions as a rule remain, which can again be utilised. 



Those nitrogenous substances which readily appear 

 in a gaseous form, such as trimethylamine and various 

 compounds of ammonia e.g., carbonate of ammonia, 

 sulphate of ammonia, &c. cannot on that account be 

 looked on as excreta. These also can, under conditions 

 otherwise favourable, act as satisfactory nitrogenous 

 nutrient materials, and it appears not improbable that 

 they may be again employed as plastic substances. 

 Accordingly, it is only free nitrogen, nitro bodies, and, 

 in the case of some classes of fungi, the nitrates, which 

 can be reckoned as under all circumstances excretory pro- 

 ducts ; and as these apparently only occur under special 

 circumstances, there is almost never a separation of 

 undoubted excrementitious nitrogenous products. Hence 

 it follows that a colony of fungi may exist and multiply 

 for an extremely long time on a very small quantity of 

 nitrogenous material, because the products of the decom- 

 position of the proteid materials constantly recombine 

 with non-nitrogenous compounds, and thus form new 

 proteid substances which may again be utilised. 



