44 HUMPHREY 
light there is a strong tendency to turn toward the light, and if 
this is not accomplished by the germ-tube, the further develop- 
ment of the young plant will at once or gradually assume the 
direction of positive heliotropism. 
DURATION OF VITALITY OF CERTAIN GREEN OR THIN- 
WALLED SPORES. 
A failure to germinate the spores of Aneura multifida major 
after they had been allowed to become several weeks old, 
induced the writer to prepare a series of cultures to test the life 
duration of the spores of Axeura, Feadula, Porella and 
Fegatella. 
The first spore cultures of all these forms were started on the 
same day of collection in order to determine whether the spores 
were ready for germination under normal conditions. Practi- 
cally all spores germinated in cultures consisting of sterilized 
earth, Knop’s solution and distilled water. I next allowed 
spores of Fegatella to dry for three days, by placing them on a 
sheet of paper on the laboratory table. These were then sown 
in the various culture media. Many of the spores had already 
germinated within the capsule but these along with all spores 
still ungerminated failed to show the slightest sign of any 
recovery after days of constant moisture and favorable light. 
Later, Professor Peirce demonstrated that one hour’s drying 
under normal conditions was sufficient to kill all spores, and 
further experiments with the spores of this species were re- 
garded unnecessary. ‘The spore wall in the case of Hegatella 
is very thin, allowing rapid loss of the water of constitution, 
resulting in a general contraction of spore contents and collapse 
of the spore wall. 
On January 12 cultures were started, sowing spores of Ahadula 
complanata collected on the ninth of the same month. Prac- 
tically all of these germinated within a few days, so another 
trial was not made till the twenty-eighth of January. Approxi- 
mately ten per cent. of the spores of this sowing failed to 
recover, the cytoplasm and other spore contents having con- 
tracted towards the center forming a brownish mass. 
On February 11 a third culture was started, the spores now 
