74 SPERMATOGENESIS AND FECUNDATION OF ZAMIA. 
but it is certain that the centrospheres occur here before and after 
fecundation in connection with spindle formation and karyokinesis, 
and are not simply cilia-forming organs of the spermatozoids, if 
indeed they can be in any way identified with such a function. 
In Dictyota, also, Mottier (89 and 90) has demonstrated the occurrence 
of centrosomes similar to those described in. Stypocaulon by Swingle, 
and in /ucus by Strasburger. They are small, deeply staining bodies, 
located in the center of a large aster, and are apparently permanent 
organs of the cell, reproducing by division during the reconstruction 
of the daughter nucleus. The centrosomes here also are intimately, 
connected with spindle formation, as in the case of Stypocaulon, the 
fibers growing into the nucleus from each centrosome in forming the 
spindle. In the above three cases, Stypocaulon, Fucus, and Dictyota, 
there is a great uniformity of the centrosomes and their action and 
appearance, and they are by all means the best worked out, most defi- 
nite, and positive cases of centrosomes known to occur in plants, though 
many other cases of centrosomes and centrospheres, ete., have been 
described. To these the blepharoplasts of Zama have only a very 
indistinct resemblance in being located at the center of a group of 
radiations. In all essential features they are totally distinct. 
In the division of the tetrospore of Dasya Davis (25) has described 
the occurrence of a body at the pole of the spindle which is supposed 
to be a centrosome or centrosphere which in one stage is broken up 
into a mass of granules, in this regard resembling the blepharoplasts 
of Zamia. In other ways and in function they are apparently very 
distinct organs from the blepharoplasts. 
In the fungi several cases of well-authenticated centrosomes or cen- 
trospheres have been described, but all of them are very distinct from 
the blepharoplasts of Zamzaand the Cycads. Inthe nuclear division in 
the ascus of Lrysiphe Harper, ina brilliant contribution, has described 
the presence of a centrosphere which takes part in the formation 
of the plasma membrane of the spore. In the nucleus just previous to 
division, the centrosphere forms a flattened disk attached to the nuclear 
membrane. Later this disk becomes surrounded with numerous radia- 
tions. The division of the centrosphere has not been observed here, 
but stages slightly before the division, when the two daughter centro- 
spheres are still near together, are figured by Harper (51, p. 251, figs. 
4,5, and 6). The centrosphere here would seem to be a permanent 
organ of the cell, increasing by division, but this is yet uncertain. — Its 
connection with spindle formation is plainly evident, the fibers grow- 
ing into the nucleus from it toward the chromosomes and finally form- 
ing the spindle. In spore formation in the ascus the centrosphere was 
found by Harper to have the novel function of forming the plasma 
membrane delimiting the spore in the ascus, a method of free cell for- 
mation which has been observed in no other place, so far as the writer 
