DEVELOPMENT OF ENERGY IN THE LOWER FUNGI. 513 



and permanently suffices for the vital processes. The 

 amount of energy is, however, regulated much less by 

 the amount of oxygen present than hy those processes 

 of decomposition in the protoplasm by the intra- 

 molecular respiration, which sets up and governs the 

 respiration by means of free oxygen. 



The whole respiratory process, whether occurring Destructive 

 with or without oxygen, is evidently of a destructive tive tissue a " 

 character, and it is absolutely necessary that a constant chan s e - 

 supply of new material should repair the deficiencies 

 which occur as the result of the decomposing activity of 

 the protoplasm and the oxidising action of the oxygen, 

 processes which furnish for the most part gaseous and 

 combustible products. As, however, those materials 

 which can be broken up in the protoplasm never 

 exist nor are taken up as nutrient materials, it is 

 evident that there must be a special process of assi- 

 milation, which consists in the absorption of the nutrient 

 materials present, and their transformation into com- 

 pounds suitable for decomposition, and which thus 

 stands in marked contrast to the destructive respira- 

 tory process. As a rule the part played by the 

 assimilatory process is in excess of the destruction, 

 and thus leads to the deposit of new protoplasm, and 

 the growth and multiplication of the cells. This is the 

 portion of the tissue change which usually alone strikes 

 the e}^e, and leads us very readily to overlook the fact 

 that, apart from the new formed material, large quan- 

 tities of the nutrient substances taken up undergo de- 

 composition in the protoplasm, and are burned up by the 

 oxygen. 



The tissue change of the lower fungi must evidently 

 go on in an exactly analogous manner to that of the 

 higher plants. Here also we have a continuous destruc- 

 tion of organic materials, usually in the presence of 

 oxygen, and in that case presenting the character of a 

 complete combustion. Here also an assimilation of the 

 new nutrient substances must provide the destructible 

 material, and at the same time must supply the require- 

 ments as regards growth and multiplication, and it is a 



