322 FUNGI 



independent organisms, the algal portion, the so-called 'gonidia,' being 

 regarded as only specially developed cells arising from the colourless cells 

 of the thallus. In 1868 Schwendener first accurately determined their 

 dual nature, though de Bary had two years before indicated the possibility 

 of this state of things in the case of the Collemaceae, &c. The dis- 

 covery so far, though sufficiently convincing, was based on anatomical 

 considerations only, but the matter was finally proved, as well as a thing 

 can be proved, by the experiments of Bornet, Treub, Reess, and Stahl. 

 Reess succeeded in producing the thallus of Collema by synthesis, and 

 Stahl went a step farther, and effected the formation of no less than 

 three species of lichen. His observations on the relations of the algal 

 and fungal elements of the lichen-thallus crowned the work of demon- 

 stration of its dual nature. Many systematic lichenologists who have 

 been unable to shake off the traditions of their study still cling to the 

 old view of the independent nature of lichens. It is hardly necessary 

 to point out that the judgment of morphologists on such matters is the 

 one to be trusted, especially as the matter has once and for all passed 

 beyond the state of trust in authoritative opinion into the perfect state 

 of complete proof. 



LITERATURE (BOOKS OF GENERAL REFERENCE). 



DC Bar}' Vergleichende Morphologic u. Biologic der Pilze, Mycetozoen u. Bacterien 

 (Leipzig, 1884). [Translation by Garnseyand Balfour, Oxford, Clarendon Press, 

 1887, referred to in text as de Bary, Comp. Morph., &c.] 



(In- the above book a complete guide to the detailed morphological literature 

 will be found.) 



Systematic. 



Saccardo Sylloge Fungorum (1882, in progress). This work is intended to include 

 all known Fungi. 



The student should also consult the numerous works of Fries, dealing 

 chiefly with Basidiomycetes ; Corda's Icones Fungorum (Prag, 1837-54) ; and 

 for British Fungi, Berkeley's Outlines of British Fungology (1860) ; Cooke's 

 Handbook of British Fungi (1871); the same author's Illustrations of British 

 Fungi (1881, in progress) ; Stevenson's Hymenomycetes Britannici (Edinburgh, 

 1886) ; and Phillips' Handbook of British Discomycetes (London, 1887). 



Diseases of Plants caused by Fungi. 

 Frank Krankheiten der Pflanzen (Breslau, 1880-81). 

 Sorauer Handbuch der Pflanzenkrankheiten (Berlin, 1886). 

 Smith, W. G. Diseases of Field and Garden Crops (London, 1884). 



Literature of Lichen-thalhis. 



This literature is too vast to be quoted here in detail, but the reader is re- 

 ferred to the following essential papers. 



Bornet Recherches sur les gonidies d. Lichens (Ann. Sc. Nat., ser. 5, xvii. and xix.). 

 Johow Ueber Westind. Hymenolichenen (Sitzber. Berl. Acacl., 1884). 



