IS THE BLEPHAROPLAST A CENTROSOME. 13 
(112, p. 185 ef seg.), and Studnicka (113), whose conclusions will be 
mentioned in some detail later on. Before stating these, however, it 
will be well to compare the blepharoplasts of the Cycads, Ginkgo, and 
ferns with some of the cases of typical centrosomes and centrospheres. 
An exhaustive comparison would extend this paper beyond its desired 
limits and would be of questionable value, because the centrosome 
question as a whole is in too great confusion to allow any final conclu- 
sion to be reached. 
One of the most typical cases of centrosomes in plants is that 
described by Swingle in 1897 as occurring in Stypocaulon (114). Here 
a minute, deeply staining, dumb-bell-shaped body occurs at the pole of 
the spindle in karyokinesis, which at the close of division divides into 
two. Both of these remain in close connection with the nuclear mem- 
brane, but travel in opposite directions until they come to lie at oppo- 
site points on the equator of the nucleus. They are always surrounded 
by rays of kinoplasm, which become very abundant during spindle 
formation and division and are not surrounded by any differentiated 
sphere of any sort, as so commonly occurs in the centrosomes of 
animals. In spindle formation the centrosome appears to be of prime 
importance, a bundle of fibers starting from each centrosome and 
gradually extending into the nucleus until the spindle is completely 
formed. Swingle’s studies were made with growing vegetative tips, 
which would indicate that the centrosome here is probably a perma- 
nent organ in all stages of growth. Centrosomes of almost exactly 
the form of those of Stypocaulon have been described by Strasburger 
(111) in Fucus. A very distinct deeply staining centrosome is described, 
which he believes to be a permanent organ of the cell, reproducing by 
division at the end of each nuclear division, thus forming two which 
control the next division. The observations of Farmer and Williams 
(37) are also of interest in this connection. They describe very marked 
centrospheres at the poles of the spindle of /wevws, in which an irregular 
number of granules, possibly representing centrosomes, can be observed. 
The number and general character of these granules is not uniform 
and the writers do not attach any significance to them. The centro- 
spheres could not be traced through the resting cell, and are apparently 
originated de novo at each period of nuclear division. The relation of 
the centrospheres to spindle formation was not traced out in detail, 
but its connection with the mature spindle and later stages of division 
is unmistakable. In fecundation no visible centrosphere is brought 
into the egg by the spermatozoid, and Farmer and Williams find no 
support for the statement of Strasburger that an apparent connection 
can be traced between the position of the two centrospheres of the 
dividing egg and the limits of the portion of the oospore nucleus which 
belonged to the sperm. The connection of the centrosphere with 
cilia formation in the spermatozoids of Fucus has not been traced out, 
