546 VITAL ACTIONS OF THE LOWER FUNGI. 



albumen, or which hydrate the saccharine material and 

 make them available for the use of the fungi, or which 

 dissolve cellulose, and thus enable those organisms 

 which live as parasites on vegetables to obtain an 

 entrance. 



The chemical nature of the materials taken up may, 

 as has been above mentioned, be very various. That 

 a transformation of these materials, a process of 

 assimilation, must occur on their entrance into the cells 

 of the fungi is probable, because it is not at all likely 

 that these different compounds are of equal value as 

 regards the different operations which occur within the 

 cell. It is true that the assimilation of the carbon is 

 not so marked as in the case of the chlorophyllous 

 plants, and more especially that carbonic acid cannot be 

 utilised. Nevertheless methylamine, acetic acid, alcohol, 

 benzoic acid, tartaric acid, leucine, &c., can without doubt 

 be converted into more complex substances if they are 

 offered as the only source of carbon ; and this first product 

 of assimilation must be built up with a certain expenditure 

 of energy, which is, it is true, not so great as in the case of 

 the assimilation of carbon from carbonic acid by green 

 plants, but which is net replaced by energy obtained from 

 the sun's rays, but by energy which must be set free as the 

 result of other transformations occurring in the interior 

 Assimilation of the cells. For the present we can only form hypotheses 

 as to the nature of the first carbon assimilation product. 

 In the case of the higher chlorophyllous plants starch is 

 frequently one of the first products ; in the case of the 

 lower fungi, however, this substance is apparently 

 with few exceptions entirely absent (only in some 

 species of bacilli and in leptothrix, see page 370). From 

 the varying nutritive value of the carbon compounds we 

 may perhaps come to the conclusion with Niigeli that 

 the first product of assimilation consists of three carbon 

 atoms, with which hydrogen and oxygen atoms are com- 

 bined, and which can then unite with a similar complex 

 of three carbon atoms to form a larger molecule of six 

 carbon atoms ; the more nearly the nutrient materials 

 approach this hypothetical body the less are the difficul- 



