On Abnormal Cell-fusion in the Archegonium; and 
on Spermatogenesis in Polytrichum. 
BY 
NORMAN WALKER, 
Assistant-Lecturer in Botany , University of Leeds. 
With Plates XIII and XIV. 
I N the year 1908 J. and W. van Leeuwen-Reijnvaan ( 12 ) published an 
account of the sexual process and spermatogenesis in several species of 
Polytrichum in which the conclusions appeared so remarkable, that it was 
suggested by Professor V. H. Blackman that a re-investigation of this 
subject might give interesting results. Strasburger ( 16 ) also, in 1909, 
in commenting upon the statements of these observers, indicated that 
further work was necessary to set these questions beyond doubt. 
J. and W. van Leeuwen-Reijnvaan state that the number of chromo- 
somes present in the cells of the sporogonium is twelve, and in the sexual 
plant six. During the last division of the spermatogenic cells a reduction 
is said to take place in the number of chromosomes, and consequently each 
spermatid receives three, and this number will be carried by the spermato- 
zoid. On the division of the egg mother-cell or central cell of the arche- 
gonium two cells of equal size are produced, the upper corresponding 
to a ventral canal cell, the lower to an egg-cell. During this division 
a reduction in the number of chromosomes is stated to take place, so that 
three is also the number received by each of these cells. While the neck of 
the archegonium is still closed the nuclei of the two cells are said to fuse, 
and the large cell resulting from this fusion is fertilized by two spermato- 
zoids. In this way four sets of three chromosomes are brought together, 
and the sporophytic number is thus established. 
The present investigation, which was commenced in 1909, was first 
directed towards the archegonium of Polytrichum and later to the last 
divisions in the antheridium. This led to further observations upon the 
division of the nucleus and upon spermatogenesis in Poly trichum formosum , 
Hedw., and an account of the results obtained, which differs in many respects 
from that of J. and W. van Leeuwen-Reijnvaan, forms the chief part of the 
[Annals of Botany. Vol. XXVII. No. CV. January, 19J3.] 
I 3 
