126 
Mycologia 
pulverized portions of the lichen in water and poured the broth 
over thelephore plants. In three months there appeared on lobes 
of the non-algicolous plants thus treated, and only on these, typical 
algicolous Cora lobes. By microscopic examination, he found 
that the pulverized lichen tissues did not grow ; but rather that the 
thelephore hyphae attacked the algae and became transformed 
into Cora lobes, which appeared only at the margin of the thele- 
phore, where its hyphae came in contact with the algae. In some 
instances the algae were left behind in time, and the Cora lobes 
reverted into thelephore forms. Thus he effected in nature the 
transformation of a non-algicolous into an algicolous fungus 
(lichen), and vice versa. Microscopic study proves that the 
spores of Dictyonema, Laudatea and Cora are alike, and behave 
exactly alike in artificial cultures. The thelephore which passes 
into the Cora form when it parasitizes Chroococcus grows into 
Dictyonema or Laudatea, according to conditions of habitat, when 
it parasitizes Scytoncma, Dictyonema being confined to small 
branches not more than finger-thick, and Laudatea occurring on 
larger branches, on dead wood, on leaves, on mosses, or on liver- 
worts. Transitional forms between Dictyonema and Laudatea 
occur commonly. Cora forms grow from Dictyonema lobes, and 
the thelephore is found growing from Cora lobes and from Diety- 
onerna lobes. Laudatea grows on Dictyonema lobes, or on Cora 
lobes, in response to change in algal host. Fungus individuals 
growing on the spherical cells of Chroococcus Avould be modified 
less and in a different manner from those growing on Scytonema 
filaments,' and so Cora is more like the thelephore than are 
Laudatea and Dictyonema, which are more modified on account 
of the nature of the algal host. We may still regard the genera 
Cora, Dictyonema and Laudatea distinct from each other and 
from their thelephoric progenitor, though any one of these may 
be produced from any other one in a short time by absence or by 
modification of the relation with an algal host. Yet this taxo- 
nomic distinction can not be insisted on very strongly. Moller’s 
research shows plainly that it would be absurd to regard such 
lichens anything but fungi. Nor do other lichens behave so 
differently toward their algal hosts as many botanists have 
supposed. 
