420 Wilson . — Spermatogenesis in the Bryophyta. 
are present at a similar stage. In consequence of these discoveries and of 
Chamberlain’s ( 18 ) statement as to the absence of centrosomes during the 
earlier stages of the spermatogenesis of Pellia epiphylla , Ikeno concluded 
that, although centrosomes are constantly present in the antheridium of 
Marchantia , in the other Bryophytes they are gradually disappearing and 
occur only in a few cell generations. 
Johnson ( 37 ) in 1904 shortly described the spermatogenesis of Mono- 
cle a Forsteri , and in this, as in Marchantia , the final division is diagonal. 
The spermatogenesis of several Liverworts was investigated by Miyake 
in 1905 ( 44 ). In a preliminary note he stated that he was unable to discover 
centrosomes in the earlier divisions in the antheridium of Marchantia poly- 
morpha. Just before division the nucleus elongates and becomes elliptical. 
An aster appears at each pole, but no centrosome is present ; the aster 
entirely disappears when the spindle is formed. At the final division 
a deeply staining body is found at each pole of the spindle, and this, no 
doubt, is the blepharoplast. Fegatella conica is similar. Asters are present 
just before spindle formation in the antheridia of Pellia , Aneura, and 
Makinoa , but in these, too, no centrosome is present. Just before the final 
division in Makinoa the cells become rounded ; neither centrosomes nor 
blepharoplasts are present at the spindle poles, but a group of granules 
is found some distance from each pole, and it is not improbable that these 
function later as a blepharoplast. In the same year Ikeno ( 34 ) reaffirmed 
his statements concerning the centrosomes in Marchantia. 
The account given by Bolleter ( 13 ) of the spermatogenesis of Fegatella 
conica agrees closely with that of Marchantia as described by Ikeno. No 
centrosomes or asters are found in the earlier divisions of the antheridium in 
material preserved in alcohol, but their presence is considered probable. 
The final division is diagonal, and no wall is produced between the resulting 
daughter-cells ; centrosomes are present during this mitosis and persist 
in the corners of the spermatids. Later on they pass to the acute angles, 
become elongated and pressed against the surface of the cell plasma, and 
finally give rise to the cilia. Meanwhile, the cells have become rounded and 
a ‘ chromatoider Nebenkorper ’, such as is described by Ikeno, has appeared. 
A ‘ Verbindungssttick probably partly derived from the c Nebenkorper ’, is 
developed between the centrosome and the nucleus. The latter decreases 
in size and becomes elongated and curved, and apparently, together with 
the ‘Verbindungssttick ’, forms the body of the spermatozoid. On the de- 
hiscence of the antheridium the spermatozoids are ejected in pairs, each 
pair being still surrounded by the wall of the mother cell. 
Humphrey ( 30 ) in 1906 described the spermatogenesis of Fossombronia 
longiseta. In the half-grown antheridium the cell-division is normal, and no 
centrosomes are present. The final division only differs in the diagonal 
position of the spindle ; no wall is produced between the resulting daughter- 
