1906] LEWIS—DEVELOPMENT OF RICCIA 129 
After a large number of divisions has taken place the antheridium 
consists of nearly cubical cells, each of which has been considered 
by earlier investigators to produce a single spermatozoid. STRAS- 
BURGER (30, p. 482) says of Marchantia polymorpha: “ Die Spezial- 
mutterzellen der Spermatozoiden sind durch fortgesetzte, sich 
rechtwinklig schneidende Teilungsschnitte angelegt worden.” CAmp- 
BELL (4) describes and figures the spermatozoid mother-cell of Pellia 
as producing two spermatozoids. IKkENO (16) discovered that in 
Marchantia each of the cubical cells undergoes another division in 
which the spindles are arranged diagonally, in the earlier divisions 
the long axis of the spindle being parallel to the long axis of the cell. 
In this last diagonal division no cell wall is formed between the 
daughter cells, each of which develops into a spermatozoid. ‘Thus 
each of the cubical cells produces two spermatozoids instead of one. 
IKENO cites several cases in which two spermatozoids are produced 
from a single mother-cell and thinks that this is probably general 
in the liverworts and mosses. 
JoHNsON (18) has described a diagonal division of the cubical 
cells of Monoclea, but he figures a wall separating the two parts of 
the cell and regards each three-cornered cell as the mother-cell of 
a spermatozoid. He dces not give the details of nuclear division 
in the earlier stages of the antheridium nor in the formation of the 
spermatozoid mother-cells. 
In the last division of the cells in the antheridium of Riccia natans 
the spindles are arranged diagonally asin Marchantia. This arrange- 
ment of the spindles is quite striking. ‘They are larger than in the 
earlier divisions and the bodies at the poles are very distinct. In 
some cases the spindles are curved (figs. 58-60). 
No wall is formed between the daughter cells, each of which 
develops into a spermatozoid. The centrosome-like bodies do not 
disappear after this division (fig. 61). "They remain in the cells, at 
first near the nuclei. The daughter cells are contracted, occupying 
the central part cf the cell cavity (figs. 62, 63). Soon the centrosome- 
like body moves away from the nucleus toward the end of the cell. 
Those in the two spermatids may be at the same end or at opposite 
ends (jigs. 63-67). When the spermatid has become somewhat 
rounded, the centrosome-like body has taken its position in contact 
