124 
Mycologia 
showed many intermediate conditions between the young mycelia 
produced from the germinating spermatia and the mature plants 
with spermagonia and apothecia. The spermatia germinating on 
the substratum were compared with those found in the sperma- 
gonia and were like these and also like those germinating on the 
thalli about the spermagonia. These results confirm those of 
Moller and are also interesting because they give further evidence 
of lichens growing with the algal hosts and reproducing by germi- 
nating upon them. 
Bornet’s classic results (32) are well known. He grew lichens 
from spores and found that they readily attack their algal hosts, 
while those that do not come in contact with the algae soon die. 
Of course he did not use proper media, or his lichens might have 
grown longer without the hosts; but this failure matters not for 
our purpose. He grew species of Collcma, Arnoldia and Physma 
chalasanum (Ach.) Arn. with Nostoc colonies, Synalissa and 
Omphalaria with Gloeocapsa, Ephebe with Sirosiphon, Opegrapha 
varia Pers., Roccella phycopsis Ach. and Pyrenida nitida (Weig.) 
Ach. with Trcntepohlia, Opegrapha filicina Mont, with the Coleo- 
chaete-\\\<it Phyllactidium and a number of lichens with Chloro- 
coccum humicola. He found Pannaria tryptophylla (Ach.) 
Mass, to grow with two algal hosts, a Nostoc and a Scytonema. 
Both of these algae often occur with the lichen in nature, and 
both often are found in the same lichen thallus. He also found 
Trcntepohlia and Phyllactidium free in the vicinity where Roc- 
cella, Opegrapha and V errucaria were growing. Opegrapha fili- 
cina Mont, is an ectoparasite, and some other lichens are also 
ectoparasites, but on unicellular or filamentous algae, among 
which the hyphae grow without penetrating into them. For in- 
stance, there is no connection between the Collema hyphae and 
the Nostoc filaments; and the Collema is ectoparasitic, except for 
penetrating into the gelatinous envelopes of the Nostoc colonies. 
The Nostoc individuals are nearly normal, but the colonies are 
much modified in form. Bornet also found Pannaria muscorum 
(Ach.) Del., Lichina confinis (Smith) Ag. and Heppia urceolata 
Nag. parasitic on two algal hosts, the last two with Chlorococcum 
humicola and a blue-green alga. He found that the other lichens 
