es 
VOLUME XXXVII NUMBER 3 
BOTANICAE GAZETTE 
MAE, 1904 
THE LIFE HISTORY OF RICCIOCARPUS NATANS. 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY. 
JOHN F. GARBER. 
(WITH FOUR FIGURES AND PLATES IX AND x) 
TueE beginning of the exact knowledge of the morphology of 
the Hepaticae dates from Hofmeister (1), who in 1850-62 pub- 
lished important investigations upon this group. Having dis- 
covered the egg cell in the archegonium, he traced the sperm to 
the surface of the egg and thus showed that the egg is fertilized 
by the sperm. He had previously announced his conclusion 
that the ordinary vegetative plants of mosses are the morpho- 
logical equivalents of the prothallia of ferns, and that in mosses 
as well as in ferns there is a true alternation of generations. 
Kny (2) gives a résumé of the literature on the morphology 
of Hepaticae up to 1867. He detected the apical cells and their 
method of segmentation in building up the thallus. He also 
described some stages in the development of the sex organs, and 
discovered the origin and manner of growth of the ventral scales. 
The thallus to him represented a fusion of stem and leaf. 
Strasburger (3) mentions and figures the canal cells, but saw 
no walls separating them. He does not mention the ventral 
canal cell as different from the others, though one of his figures 
clearly shows it. 
Leitgeb (6) in 1874-82 published comparative studies of the 
entire group of Hepaticae. In the Ricciaceae and Marchantia- 
ceae he described the structure of the thallus and its method of 
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