Cell Structure, Growth and Division in the Antheridia of Polytrichum etc. 169 
from the presence of a large amount of kinoplasm which tends to occupy 
a fairly definite position relative to the nucleus. 
The appearanee of the polar plates suggests a comparison with the 
“spindle wall” (Osterhout, 1902), which appears in the pollen mother 
cells of Agave, outside of and surrounding the nuclear membrane, and 
from which fibers, later to form the spindle, grow toward the nucleus. Com- 
parison may also be made with the kinoplasmic aggregations which appear, 
in connection with the formation of polar caps, in the cytoplasm of many 
vegetative cells (Strasburger, 1900). In each case there may well be 
a real analogy, based upon similarity in composition and function; but 
no reason appears for suspecting any homology between the three sets 
of structures. 
The question naturally arises why there should be so marked a develop- 
ment of kinoplasm in the androgones, in contrast to the conditions in the 
vegetative cells. One possible answer is that the rapid succession of 
nuclear and cell divisions in the antheridium necessitates a considerable 
accumulation of kinoplasm at the beginning of the series, since there will 
be little opportunity later for such formation of new kinoplasm as occurs 
in tissues wliose cells undergo a longer period of rest and growth between 
successive mitoses. This notion is supported by the observable diminution 
in the amount of kinoplasm as the number of androgones increases, and 
by the fact that the androcyte mother cells, like vegetative cells, are quite 
lacking in kinetosomes. This explanation of the unusual abundance of 
kinoplasm in the androgones is presented merely as a Suggestion; it may 
be in a measure tested by a study of the antheridia of other plants wherein 
the conditions are comparable to those in the antheridia of Polytrichum. 
The Blepharoplast. 
From such studies as have been made of spermatogenesis in c-haraceae, 
bryophytes, pteridophytes, and those spermatophytes that possess motile 
antherozoids, it appears that in each case a dark-staining cytoplasmic 
body, the blepharoplast (Webber, 1897 h), is present in the androcyte, 
before or during the metamorphosis of the latter; and that the cilia of the 
antherozoid, in whatever number, grow out from the blepharoplast or 
its derivatives. But as to the time and place of origin of the blepharoplast, 
its relation to mitosis, and its possible homologies, the widest difference 
of opinion prevails. 
Early references to what is probably the blepharoplast of Chara 
[as Belajeff (1894) points out] appear in the descriptions by Mettenius 
(1845) of refractive granules in or dose to the androcyte nucleus, and by 
