INFLUENCE OF LIGHT OX El'MYCETES. 57 



(Innvn on solid media this fungus seems to develop sponnigia 

 under Jinv kind of illuiiiiiiution. A fact of not less inii><JiUince 

 than the capacity of heat rays to replace light rays, is that 

 demonstrated by liuKKKLU (IV.), in tin- ease of J'iluhulua tiiirn^ 

 s/>nriif, a fun;,Mis of the Mihorarea family (.^ 235), namely, the 

 after effect of illumination. When kej)t in the dark from the 

 bejiinnin'', the mveelium of this fun-nis remains entiiely and 

 permanently barren ; but if exjtosed to the light foi- a eouple of 

 hours, and then plaeed in the darkl)ef()re any signs of fruetifica- 

 tion appear, the sporangia will develop, though ordinarily they 

 oidy do .so in the light. 



Still more scanty is our knowledge of the influence of light 

 on the internal life, /.<. the chemieo-physiological ea}>aeity, df the 

 Eumycetes. In fact it i.s almost entirely confined to a series of 

 <ibservati(>ns made on respiration (^i 23.S), /.<. the exhalation of 

 carbon dioxide. The lir.st experiments were tomlucted by 

 Wilson (I.), who failed to discover any influence due to light; 

 and also by Bonnieh and Mancjix (I.), and Plhiewitsch 

 (II.), who experimented with various pileated fungi (iiittr alia, 

 Aif'iriciis cat/iji'fiti.-') and J'liijrtDiii/ff-s iiifi'ih<, and in all cases 

 found respiration hindered by dilfused daylight, the .strongest 

 elTect being produced by the least lefrangible rays. The.se 

 experiments, however, were of a merely preliminary character, 

 no regard having been paid to the circum.stiince that the ex- 

 haled carbon dioxide may originate from fm) distinct vital 

 processes ; viz. either from the conversion of matter in the 

 course of Ijuilding up the cell, or from the prtK-ess of combustion 

 within the full-grown cell for the purpo.se of replacing di."<sipated 

 internal energy. DrcLAlx (X.) was the lirst to point out to 

 mvcolo''ists this dilYerence, which was alreadv well known in 

 animal physiology. And, as a matter of fact, the subsecjuent 

 work of Elkvinc. (I.) — on Miirtir rarmioKUs, Atfjteiymiin ni(jer, 

 A. t!arrsi'rn.<, ami I'liiiri/liiiin (jlaiiriim — led to the discovery 

 that this dilYerentiation of tlie two source.s uf carlH)n dioxide is 

 also applicable in the case of fungi. In older cultures, wherein 

 the foodstuff is chiefly consumed in order to maintain the vital 

 energv, no apjKirent influence is exercised by light on the 

 volume of exliaU'd larbon dioxide. On the itther hand, a retard- 

 ing effect is i)rodueed V\v light in younger eulture.s, i.e. those in 

 which the reproduction and growth of the cells is procei-tling 

 l>riskly. All the above-mentioned workers regarded the total 

 amount of car\>on dioxide, liberated l)V the cultinvs under 

 observation, as a mea.sure of the respiration ; but H. Koi.kwitz 

 (I.) took into oonsideratitui. as a by no means negligible .<(auve 

 of error in prolonged experinu>nts, the gradual decompo.»itii>n 

 sustained by oxalic acid under the influence of light (>5 21), since 

 this acid is of fretpuMit occurrence among the metabolic prinluctij 

 of fungi. On excluding this source of inaccin-;u'v, by examining 



