452 
Wilson . — Spermatogenesis in the Bryophyta . 
Summary. 
1. In Mniurn hornum and A trichum undulatum the divisions of the 
spermatogenic cells are normal, and no centrosomes are present. The final 
division is not of the diagonal type which is found in several of the Hepa- 
ticeae. No reduction in the number of the chromosomes takes place at the 
final mitosis. 
2 . In Pellia epiphylla centrospheres and probably centrosomes are 
present during the later divisions in the antheridium. The blepharoplast is 
probably derived directly from the centrosome. 
3. In the spermatid of Mninm hornum a number of bodies become 
separated from the nucleolus. These pass into the cytoplasm and there 
give rise to a number of rod-like structures. The rod-like structures, by 
coalescence, finally form a hollow spherical body, for which the name 
limosphere is suggested. The nucleolus then divides into two masses, 
which both pass into the cytoplasm ; one of these functions as the blepharo- 
plast, while the other gives rise to the accessory body. 
4. In the spermatid of AtricJmm undulatum three bodies are separated 
from the nucleolus and pass into the cytoplasm. The body first produced 
functions as the blepharoplast. The limosphere arises from one of the 
remaining bodies, while the other gives rise to the accessory body. 
5. In Pellia epiphylla a limosphere and accessory body are present in 
the cytoplasm of the spermatid. Their origin was not determined. 
6. In all of the three plants under consideration the blepharoplast 
passes to the periphery of the spermatid. A thread-like structure is pro- 
duced in connexion with the blepharoplast, which passes along the inner 
contour of the cell membrane. The nucleus passes to the periphery and 
lies in contact with the thread. Elongation takes place in the nucleus, and 
the latter, together with the thread, produces the entire body of the sperma- 
tozoid. The limosphere and accessory body persist in the almost mature 
spermatozoid, and in all probability are found ultimately in the vesicle. 
In conclusion, I wish to express my thanks to Professor Farmer, 
F.R.S., for his constant help and valuable advice throughout the course of 
the investigation. I also wish to thank Mr. F. J. F. Shaw, B.Sc., A.R.C.S., 
for the collection and preservation of material of Pellia epiphylla . and for 
the preparation of a considerable number of sections of this plant. 
