RECENT RESEARCHES INTO THE NATURE OF LICHENS. 1-15 



The last paper mentioned by Mr. Archer in his resume is the 

 important one by Treub/ published in November 1873. In the 

 'Flora' for January 187-1, J. Miiller hastens to combat the 

 results at which Treub had arrived. He regards the question as 

 still an open one, in spite of the recent publications of Treub and 

 Bornet, and maintains firmly the accuracy of his own observa- 

 tions in which he distinctly traced the development of the 

 gonidium from the hypha in Sijnalissa Salevensis. He goes so 

 far as to say that, even if his own observations were inaccurate, 

 the new theory cannot be considered as established until it is 

 ascertained that the spermatia give rise to hyphoid and not to 

 gonidial products. Miiller's paper was soon followed by another 

 on the same side from the pen of Nylander.^ In it are repeated 

 most of the objections which this distinguished lichenologist had 

 already raised to the acceptance of Schwendener's theory, and 

 attention is particularly drawn to the fact that those Algae which 

 are regarded by the supporters of the theory as playing the part 

 of gonidia in various Lichens — such Algae, for instance, as Cora, 

 Dichonema, Scytonema, Sirosiphon — are held by him to be them- 

 selves of the nature of Lichens. From this point of view, 

 the new theory of the structure of the lichen-thallus is simply 

 absurd. 



In the July Number of the ' Popular Science Review,' of the 

 same year, the Rev. J. M. Crombie, comes forward as another 

 opponent of the new doctrine. In his article he gives a brief 

 history of the whole discussion, and sums up strongly in favour 

 of the older views. He is especially severe upon one of Bornet's 

 " strong points," viz., the identity of Protococcus viridis with 

 the gonidia of Physcia parietlna. He admits the similarity ex- 

 isting! between these organisms, but cannot recognise it as 

 amounting to identity, for the gonidia of Physcia are larger and 

 multiply less actively, while Protococcus multiplies very rapidly. 

 Some facts, to which attention will subsequently be called, will 

 shew that these differences of habit do not suffice to prove these 

 organisms to be distinct. 



Later on in the year an elaborate defence of the older views 

 was published by Korber.^ He lays down three propositions, 

 (1) that the tissue in which the gonidia of a Lichen are em- 

 bedded is not of a fungoid nature ; (2) that the gonidia are not 

 true Algae; and (3) that Lichens are not the expressions of a 

 condition of parasitism. In support of his first proposition he 

 recalls the difl'erences which Von Krempelhuber pointed out as 

 existing between the tissues of Lichens and those of Fungi, but 



^ ' Onderzoek. over de Natuur der Lichenen. Leiden.' 



- 'Flora,' abstracted by the Rev. J. M. Crombie in ' Grevillea,' vol. ii. 



^ 'Zur Abwehr der Scliwendener-Buruet'sclieu rieclitentlieorie/ Breslau. 



