- 8 4 - 
minate in contact with the hymenial algae that had been expelled with the spores 
and had stuck to them. 11 These and other experiments soon demonstrated be- 
yond a doubt the dual nature of Lichens. 
There arose, however, the question as to the nature of the relationship of 
the two components towards each other. Schwendener called it parasitism, and 
he and his followers uniformly agreed to classify Lichens as Fungi, to all of which, 
as already stated, the systematists objected very strongly. DeBary called the 
relationship symbiosis — a union for mutual good, enabling these plants to exist 
where neither of the components could exist alone — and this I believe is the pre- 
vailing view. Pfeffer, for example, in his “Physiology of Plants,” Vol I, page 
370, says: “Lichens are good examples of reciprocal symbiosis, for they are 
specific organisms formed by the union of a fungus and one or more algae, and 
can frequently withstand climatic conditions to which the isolated component 
parts succumb. The fungus, especially in those lichens which grow upon bare 
rocks, obtains organic food from the algae, while the fungal mycelium supplies 
the latter with water and salts, or even with proteids when the symbiotic algae 
are peptone-organisms.” These views are, no doubt, all due to the influence of 
Reinke, the greatest of the upholders of the autonomous nature of Lichens. He 
calls the relationship of Fungus to Alga “consortism, ” and says: “We have, 
therefore, in the thallus of Lichens, a consortism, the components of which form 
a unit, a morphological individual, somewhat as the different tissues in a higher 
plant unite to form the individual. The fact that the alga can exist independ- 
ently is dependent upon its ability to assimilate carbon. In the state of con- 
sortism, at least in the heteromerous thallus, the alga is nourished by the enclos- 
ing fungus, that is, it receives from the hyphae the necessary minerals, nitrogen, 
hydrogen and water. The alga in return supplies the fungus with the essential 
carbon compounds. From this it is evident that the components (Alga and 
Fungus) are biologically associated, mutually dependent upon each other for 
the formation of the organic substances required for the upbuilding of the com- 
mon body. ” 
However, the question does not seem to be any nearer solution to-day: each 
side has its followers. Several years ago, (1911) Professor Fink, of Miami, Ohio, 
wishing to get some sort of an idea how botanists, and especially lichenists, stood 
upon the question “Should the Lichens be maintained as a distinct class of plants 
or should they be distributed among the Fungi? 12 .... , wrote to 75 Amer- 
icans and 75 Europeans. Of the 115 replies received, 19, or about 17%, favored 
distribution; 14, or about 12%, thought that Lichens might be distributed, but 
for one reason or other prefer that they should remain a distinct group. In other 
words, 83% of the 115, believe that Lichens should be maintained as a distinct 
group. A closer examination of the replies showed that the lichenists were 
nearly unanimously in favor of maintaining the group Lichens. 
“Stahl. Beitrage zur Entwickelungsgeschichte der Flechten, II, Leipzig. 1877. 
12 Mycologia, September, 1911, and May, 1913. 
