THE 
AMERICAN NATURALIST 
VoL. XXXIV. April, 1900. No. 400. 
THE RELATION OF FUNGUS AND ALGA IN 
LICHENS. 
GEORGE JAMES PEIRCE. 
IF one did not constantly read, even in the newest text-books 
for older! as well as for younger students,? that the associa- 
tion between fungus and alga in lichens is uninjurious to the 
latter, I should not feel impelled to add to the already volumi- 
1 See Textbook of Botany, by Strasburger, Noll, Schenck, Schimper, translated 
by Porter (Macmillan Company, 1898), p. 375: The fungus derives its nourishment 
Saprophytically from the organic matter produced by the assimilating alga, with- 
out at the same time behaving as a parasite and injuriously interfering with its 
vegetative activity. 
In the fourth German edition (received by me, Jan. 19; 1900, as a separate) 
Schenck says, p. 336: Was das Verhültniss von Pilz zu Alge anbelangt, so um- 
spinnt der Pilz mit seinem Mycel die Algenzellen, schliesst sie in ein Hyphen- 
gewebe ein und ernährt sich von den durch die assimilirenden grünen Algenzellen 
erzeugten organischen Stoffen ; er kann aber Haustorien in die Algenzellen hinein 
entsenden und sogar deren Inhalt aufzehren. 
? See Coulter’s Plant Structures (D. uae & Co., 1899), p. 80: In the 
case of lichens the symbionts are thought by some to be mutually helpful, the 
alga manufacturing food for the fungus, n sponse providing protection and 
water containing food materials for the alga. Others do not recognize any spe- 
cial benefit to the alga, and see in a lichen simply a parasitic fungus living on 
the products of an alga. In any event the algz are not destroyed, but seem to 
thrive. 
Li 
245 
