RECENT OBSERVATIONS ON THE GONIDIA QUESTION. 127 



which had furnished the spores; by making very thin sections 

 of these pieces of bark the progress of germination was 

 observed. The method followed by Tulasne of letting the 

 spores germinate on stone I never adopted, because it appeared 

 to me that the due examination of the process of germination 

 is by this plan very difficult; one must then, indeed, either 

 remove the germinating spores from the substratum, — and to 

 do this without injury is very difficult, especially Avhen the 

 germinating filaments are very long — or one must make 

 the microscopic observation by means of reflected light, 

 in which case certainly no very good results are to be 

 expected. 



On two occasions I caused the germination to take place 

 in the presence of a small quantity of the ash of the lichens ; 

 if the substratum Avere then moistened by vapour some of the 

 ash-constituents would thus be dissolved, and serve for food 

 to the germinating filaments, in case this inorganic food were 

 necessary in order to cause the gonidia to originate. 



A great number of the experiments were partly carried 

 on in the dark, because there was thus perhaps more chance 

 of good results ; in the new formation of cells light can, 

 indeed, not only be done without, but it ordinarily operates 

 even injuriously, and darkness favorably.^ 



From the middle of April to the beginning of July, 1873, 

 I made forty experiments with spores oiXanthoria, Ramalina, 

 and Lecanora. 



Two to eight days after the sowing the first appearances 

 of germination make themselves evident, the more unfavora- 

 ble the circumstances so much the later. Amongst the cir- 

 cumstances unfavorable to germination are a too copious 

 supply of water on the substratum, and the direct proximity 

 of other objects as well as of other spores. If many spores 

 lie, for instance, on the top of one another this impedes ger- 

 mination. The very imperfect germination of spores placed 

 under none of these unfavorable conditions shows that there 

 must be still olher conditions which are not understood. 



About a month after the sowing the protoplasm becomes 

 in great part used up in the formation and elongation of the 

 germinating filaments. In the first year of my experiments 

 the germination very rarely reached the last stage, wherein the 

 spore is wholly empty and the protoplasm used up, probably 

 often owing to the influence of the first-mentioned unfavorable 

 circumstances, but above all to the early occurrence of" a mould 

 upon the substratum on which the spores were placed, whereby 



* See Sachs, ' Experiai. Pbysiologie,' pp. 30, 31. 



