Woodburn. — - Spermatogenesis in certain Hepaticae. 305 
evidently of a double nature (Figs. 47 and 48). Since this is not a reducing 
division the double nature is certainly the result of a split. The chromo- 
somes are now quickly differentiated. Whether the large loops and 
enlarged portions of the spireme (Fig. 48) separate as individual chromo- 
somes must be left for further investigation. In sections cut in the plane 
of the equatorial plate the chromosomes are easily counted, and, as already 
stated by other investigators, the number is clearly eight. 
During the prophase the nuclear cavity is not so often found to be 
filled with the homogenous or very finely granular substance as observed 
regularly in Marchantia. This condition, however, prevails to some extent 
(Fig. 48). But in this figure the nuclear membrane has practically dis- 
appeared, and there are indications in the surrounding cytoplasm that 
spindle fibres are beginning to form. These are at first very fine and evenly 
and closely distributed ; later they collect into coarser strands attached to 
the chromosomes at the equatorial plate (Figs. 50 and 51). The appear- 
ance of the chromosomes in this position is quite similar to that in Mar- 
chantia (Fig. 28 a) and Porella (Fig. 8). The individual chromosomes 
cannot always be distinguished. The spindle fibres are evidently active 
in laying down the cell plate (Fig. 52, Fegatella , and Fig. 10, Porella ), as 
is the case in the higher plants. 
The cytoplasm is quite similar to that of Marchantia. At no time is 
there any evidence of a centrosome-like body. This agrees with Escoyez’s 
(W) observations on the same plant. Bolleter (’ 05 ), however, concluded 
that, since he saw bodies in the sperm cells resulting from the diagonal 
division, and that, following Ikeno’s conclusions for Marchantia , these 
bodies were centrosomes, therefore they must surely be present in the 
preceding spermogenous divisions, although he did not observe them. 
In Astcrella my studies were less extensive, but some sharply defined 
spindles were found (Figs. 61 and 62). Very minute dots were sometimes 
seen occupying the poles of the spindle, but these were very insignificant as 
compared to the size and appearance of granules lying in various places 
throughout the cytoplasm. Nothing was found in this study as far as 
pursued which resembled centrosomes in appearance or behaviour. 
The Oblique Division. 
Fig. li shows two cells from an antheridium of Porella , which is 
evidently ready to enter the last division, as indicated by the size of the 
organ and by the number and size of the cells. The nuclear network is 
quite coarsely granular, with small chromatin particles, and contains a small 
nucleolus. The cytoplasm is rather finely and evenly granular. The last 
division was not found, although hundreds of sections were examined for 
this particular stage. Pairs of sperm cells, however, just succeeding the last 
division were found, but whether these are the result of a diagonal division 
