Fink: Classification of Lichens 
157 
structure and fruiting bodies. The bridges which connect lichens 
with other fungi are not few but many. Since it is thoroughly 
demonstrated that the lichen is parasitic, or partly parasitic and 
partly saprophytic on the alga, there is no longer even a poor 
excuse for a “ consortium ” or an “ individualism ” hypothesis. 
9. The parasitism of lichens on algae is peculiar in that the uni- 
cellular or the filamentous hosts are usually enclosed by the par- 
asite, which may carry more or less food material to its host. 
The host inside of the parasite is placed in a disadvantageous posi- 
tion with reference to carbon assimilation and may depend, for its 
carbon supply, more or less upon material brought from the sub- 
stratum by the parasite. Some algal individuals not yet paras- 
itized may be found in most lichen thalli. 
10. The lichen is a fungus zvhich lives during all or part of its 
life in parasitic relation zvith the algal host and also sustains a re- 
lation zvith an organic or an inorganic substratum. The definition 
may need modification later to recognize Elenkin’s hypothesis, in 
part or fully. 
List of Works Cited 
1. Acton, Elizabeth. Botrydina vulgaris Brebisson, a primitive 
lichen. Ann. Bot. 23 : 579-585. pi. 44 and three figures unnum- 
bered. 1909. 
2. Arcangeli, G. Sulla Questione dei Gonidi. Nuov. Giorn. Bot. 
Ital. 7 ; 270-292. 1875. 
3. Archer, W. A further resume of recent observations on the 
gonidia question. Quart. Journ. Mic. Sci. II. 14 : 1 15-139. 1874. 
4. Archer, W. On apothecia occurring in some Scytonematous and 
Sirosiphonaceous algae, in addition to those previously known. 
Quart. Journ. Mic. Sci. II. 15: 27-37. pb 3- 1875. 
5. Artari, A. Ueber die Entwicklung der griinen Algen unter Ahs- 
schluss der Bedingungen der Kohlensaure-Assimilation. Bull. 
Soc. Imp. Nat. AIoscou II. 13 : 39-47. /. 1-2. 1899. 
6. Artari, A. Zur Ernahrungsphysiologie der griinen Algen. Ber. 
Deutsch. Bot. Ges. 19: 7-9. 1901. 
7. Artari, A. Ueber die Bildung des Chlorophylls durch griine 
Algen. Ber. Deutsch. Bot. Ges. 20: 201-207. 1902. 
8. Bachmann, E. Die Beziehungen der Kalkflechten zu ihrem Sub- 
strate. Ber. Deutsch. Bot. Ges. 8: 141-145. pi. p. 1890. 
9. Bachmann, E. Der Thallus der Kalkflecten. Wiss. Berl. Prog. 
Realsch. Paulen. 1892: 1-26. pi. i. 1892. 
