Spermatogenesis in certain Hepaticae. 
BY 
WILLIAM LOGAN WOODBURN. 
With Plate XXV. 
D URING recent years considerable interest has been shown in the 
study of spermatogenesis in the Rryophytes, Pteridophytes, and other 
cryptogams, as evidenced by the contributions on this subject. It has been 
difficult to arrive at correct conclusions in regard to the true nature and 
history of spermatogenesis in some of these forms, especially in the 
Bryophyta. Two difficulties in particular have, as a rule, been encountered. 
In the first place the cells are small, and certain important details of their 
contents are hard to differentiate. In the second place the process of 
spermatogenesis involves such a complete, and at times rapid, transforma- 
tion of the individual cell that the origin and fate of certain parts are difficult 
to trace, and the nature and function quite as hard to determine. These 
difficulties are evidenced by the various opinions in regard to the process 
presented by the different investigators. 
It was with the hope of obtaining further facts which might clear up 
somewhat the problems encountered in tracing the development of the 
sperm in some forms of the Hepaticae, that a study of spermatogenesis in 
Porella and other Liverworts was undertaken. 
The first detailed account in recent years, treating of spermatogenesis 
in the Hepaticae, was given by Ikeno (’OB) for Marchantia polymorpha . He 
discusses the early divisions- in spermogenous cells, the last or oblique 
division, and the development of the spermatozoids. In all divisions of 
spermogenous tissue he finds a body which he calls a centrosome occupying 
each pole of the spindle. This centrosome he describes as separating from 
the chromatic mass in the nucleus, moving towards the nuclear membrane, 
and passing through the latter into the cytoplasm. Here it divides and the 
daughter bodies move to opposite sides of the nucleus, where they apparently 
take part in the formation of the spindle. They occupy the poles of the 
spindle until late anaphase or telophase, when they disappear, but reappear 
in the prophase of each successive division. In the last spermogenous 
division, the spindle lies diagonally, and the cell is consequently separated 
[Annals of Botany, Vol. XXV. No. XCVIII. April, 1911.] 
