RECENT OBSERVATIONS ON THE GONIDIA QUESTION. 131 



the homoiomerous lichens in his culture of Collema glau- 

 cescens. 



In any case, after the Co/Zewa-cultures, it remained of 

 great importance to confirm experimentally the presumption 

 of a double nature for the heteromerous lichens, and the 

 more so as such a man as Cohn acquiesces in Schwendener's 

 views for the homoiomerous lichens, and still he regards the 

 same views as bearing upon the heteromerous lichens as 

 untenable.^ 



Before describing the plan and results of my own 

 cultures I may be permitted to mention what has been done 

 in this direction by others. 



Woronine obtained no positive result by bringing theca- 

 spores of Parmelia pulverulenta into contact with the young 

 gonidia in a drop of water,^ The second who has made 

 experiments in the culture of spores and algse together is 

 Bornet, who says^ — 1 placed on the fragments of lime-stone 

 freshly broken and on fragments of bark which I had boiled 

 in water for about a quarter of an hour a layer of Protococcus 

 tnridis and some spores of Parmelia parietina. The Pro- 

 tococcus taken on a damp and shady wall was almost pure. 

 There were wdth difficulty to be found mingled some Micro- 

 coleus filaments, a very slender Oscillaioria and a small number 

 of Cladosporium-s^oves ; but 1 did not perceive any trace of 

 spores or filaments of lichens. The Protococcus dihited in 

 water rapidly became resolved into Zoospores. Other frag- 

 ments of stone and bark received exclusively Protococcus or 

 spores. . . . Germination took place in some days in 

 the manner described and figured by Tulasne, Towards 

 the fifteenth day the hypha Avas already large and ramified. 

 AVherever it came in contact with the cells of the Proto- 

 coccus, either isolated or in groups, it adhered either directly 

 or by a lateral branch. I may add that the hypha attached 

 itself exclusively to the Protococcus, and not to other bodies 

 mingled therewith. It is by hundreds that I have obtained 

 these germinations, and I have been able to ascertain 

 with certainty that I was not deceived by accidental 

 adherences. 



The spores sown apart at the same time as the others 

 germinated alike, but became much less ramified, and did 



' " Sitzuugsbeiiclite d. Bot. Sect. d. Scliles. Gesellscliaft," Ji-Eot. 

 Zeitung,' 1872, p. 16. 



^ Woronine, " Rech. sur les gonid. du Lichen Parmelia pulverulenta" 

 'Ann. d. Sci. Nat. Bot.,' 5 ser., t, xvi, p. 32 1. 



3 Bornet, " Recherches sur les Gonidies des Lichen," in 'Ann. d. Sciences 

 Jiaturelles,' 5 sen, t. xvii, p. 65, 1873. 



