13JJ \V. ARCHER. 



The brief result of experiments made by Bornet in causing 

 lichen-spores to germinate in company with algsc is incor- 

 porated below with an English version of the record of the 

 experiments instituted for this purpose by Dr. MelchiorTreub, 

 and detailed by him in a Memoir laid before the University 

 of Leiden in "November last,^ The author of this memoir begins 

 by giving in the first section an interesting and com- 

 plete epitome of the history of Lichenology — more especially 

 in its bearing on the subject in question — from Tulasne to the 

 present. It is a pity that so thorough a resume of the scat- 

 tered literature of the subject is written in Dutch, a language 

 not much read in this country ; however, the more important 

 of the references touching on the "gonidia question " have 

 already been placed before the readers of this journal. The 

 second section of the Treub Memoir is devoted to an ac- 

 count of the author's original researches in 1872 and 1873 

 on this question, and is repeated below pretty nearly in full, 

 for, notwithstanding that a large proportion of his experiments 

 ended abortively, much interest attaches to them. He vdti- 

 mately arrived at results in accordance with those of Bornet, 

 and, so far as they go, apparently very much in favour of the 

 de-Bary-Schwendener theory. 



The two following paragraphs allude to Reess's experi- 

 ments, already referred to in a previous number of this 

 journal, and to Miiller's views as given above : — 



1. The conclusion drawn by Fries from the experi- 

 ments of E-eess that, if parasitism in lichens were true, 

 the parasite should originate first and then the host, is 

 incorrect. The colonies of Nostoc lichenoides with which 

 Reess experimented must have reached even the size of a 

 pea; it is therefore not to be wondered at that the ger- 

 minating filaments of the spores, which were designedly 

 placed upon the iVo^^oc-colonies, did not become long 

 enough to be able to reach the substratum, and, by taking 

 up food from it to enable the filaments Avhich had penetrated 

 into the Nostoc to continue growing. If, then, Collema spores 

 merely fall ujjon freely growing iVb^/oc-colonies, Collema would 

 not necessarily originate in consequence. This does not, how- 

 ever, prevent iVbs^o c-colonies which have already grown for 

 some time upon a substratum being subsequently able to pass 

 over into Collema ; for this it is only necessary that the spores 



' Treub, ' Onderzoekingen over de Natuur der Lichenen,' Leiden (22 

 November, 1873). Previously the author had published a brief communica- 

 tion, " Lichenencultur,' in ' Botanische Zeitung," No. 46, Nov. 1S73, but 

 written in September, in anticipation of his more copious Memoir, giving the 

 complete LisLury of the question and the full details of his experiments. 



