PHYSIOLOGY AND MORPHOLOGY OF CALIFORNIA HEPATICZ 33 
any consequence fell on the twenty-first of August, but liver- 
worts barely revived by it were overtaken by a period of dry, 
hot weather which lasted till September 23, when the rainy 
season began. It might justly be assumed that the resumption 
of growth, as regards Fossoméronza at least, began at this time, 
More than the usual amount of rain was recorded for October 
and November and growing conditions were very favorable. 
Material collected in early February showed sporongia in which 
the spore-mother cells were preparing to pass into the tetraspore 
condition, and six weeks later material was collected bearing 
ripe spores and elaters. From this it will be seen that, having 
a favorable rainy season, the time required to produce ripe 
spores is approximately six months after the first rains of any 
consequence. Judging from the advanced development in which 
one finds antheridia and archegonia at the close of the summer 
season, fertilization must occur within a few weeks after 
resumption of growth is well established. 
With regard to the plants that had grown unchecked through- 
out the summer, it must be noted that temperature and humidity 
conditions are widely different from those prevailing in winter. 
Though the plants were well irrigated, the atmospheric condi- 
tions were such as to influence to some extent the growth and 
behavior of the thallus and fruiting organs. Assuming, how- 
ever, the same rate of development of the sporogonia for these 
plants as for those grown in winter, fertilization must have 
occurred during July and later. Growing in a paraflin-coated 
glass dish containing Knop’s nutrient solution, the writer has 
under observation several plants of Fossombronza, placed there 
a month ago in air-dry condition as nearly free from soil parti- 
cles as they could be rendered by the use of a fine, stiff brush. 
Antheridia and archegonia then in the initial stages of develop- 
ment are now about as far advanced as were the oldest of those 
observed as soon as the plants had revived —in the course of 
twelve hours. These oldest ones are now maturing. It will 
be shown elsewhere, however, that Knop’s solution affords a 
very active stimulus to development of the thallus and fruiting 
organs, probably shortening the time of their normal develop- 
ment considerably. 
Proc. Wash. Acad. Sci., January, 1908. 
