Pellia epiphyllci, (L.) Cor da. 203 
the elaters had not developed spiral thickenings, and the spores had only 
reached the tetrad stage. 
One sporogonium was found in a still more aborted form. In this case 
only a few divisions had taken place in the fertilized egg, which contained 
fungal hyphae, though there were none in the thallus near it. 
Apparently, therefore, there are three methods by which the fungus 
may enter the sporogonium : 
(a) Hyphae from the thallus penetrate to the base of the foot, enter it, 
and ramify through the tissue of the sporophyte. In this case the spores 
of the liverwort may form young gametophytes before the fungus obtains 
a hold on the capsule, but they will not grow farther. 
(< b ) Hyphae may enter the fertilized archegonium and ramify through 
the developing sporogonium, which in this case remains abortive to a varying 
degree, its development ceasing almost at the beginning, the sporogenous 
tissue reaching the spore mother-cell stage or the tetrad stage — but the 
spores never germinate within the capsule. 
( c ) The hyphae may enter in both the above ways. Here, too, the 
sporogonium usually remains abortive. * 
Isolation of the Fungus. 
Repeated attempts were made to isolate the fungus from the thallus 
of the liverwort. Portions of the thallus were broken off, teased out with 
a sterilized platinum needle, sterilized in a o-i per cent, solution of mercuric 
chloride, and placed on plates containing various nutrient media. The 
fungus, however, did not grow. The experiments were repeated without 
sterilization in mercuric chloride solution, it being thought that the latter 
process might have killed the fungus, but no better success was obtained. 
Various species of Penicillium , Eurotium , Mucor , &c., as well as 
Bacteria were obtained on some of the plates in the latter case, whilst 
others remained sterile, but the endophyte was inactive. Meat agar, Pellia 
extract agar, Pellia extract gelatine, potato glycerine agar, malt agar, 
synthetic media with the addition of dextrose, or dextrose and peptone, 
and beerwort agar were used in these trials. Some cultures were incubated 
at a temperature of 23 0 C. ; others were kept in darkness at room tem- 
perature. 
Hanging-drop cultures were also tried. Rhizoids containing fungal 
hyphae were removed from the thallus, and placed in drops of various 
media (beerwort, Pellia extract, and distilled water). These were examined 
under the microscope at intervals, but, although in some cases fungal hyphae 
were seen emerging from rhizoids, they did not develop farther. 
Upon the discovery of fungal hyphae and spores in the sporophyte, 
attempts were again made to isolate the fungus. Pieces of infected 
capsules were placed by means of a sterilized needle on agar plates. 
