Cell Stracture, Growth and Division in the Antheridia of Polytrichum etc. 175 
sides of this question. Strasburger (1900) has advanced a further argu- 
ment based upon the derivation of antherozoidsfrom the ciliated spores and 
gametes of the green algae. In the formation of the swarm-spores of 
Vaucheria, Oedogonium, Cladophora and Bryopsis, he finds that the cilia 
originate in each case from a body which arises as a thickening of the plasma 
membrane, at a region where the latter has been temporarily in contact 
with the nucleus. Strasburger concludes that the blepharoplasts in 
higher plants are masses of active kinoplasm homologous with these 
cilia-forming Organs in the algae which he studied; but that in separating 
themselves from the plasma membrane and coming to lie free in the cyto- 
plasm, they have taken on certain characteristics (for instance, an ap- 
parent relation to the mitotic figure) which suggest an analogy with true 
central bodies. The history of the blepharoplast in the developing zoöspore 
of Derbesia, studied by Davis (1908), in the main Supports Strasburger’s 
c-ontention. In this case the blepharoplast is reported to be formed just 
within the plasma membrane, from granules which originated in the 
neighborhood of the nucleus and migrated outward along Strands that 
eonnect the nucleus and the plasma membrane. 
Ikeno (1904), on the other hand, has urged that the blepharoplasts 
of the algae, interpreted by Strasburger as thickenings of the plasma 
membrane, may really be centrosomes or their derivatives, which, like 
the blepharoplasts of higher plants, take a peripheral position preparatory 
to cilia formation. In Support of this Suggestion, he cites Timberlake’s 
(1902) Observation of bodies resembling centrosomes at the spindle poles 
of mitoses preceding spore formation in Hydrodidijon. In the mature 
swarm-spore, at the base of the cilia, is a body, distinct from the plasma 
membrane, which Ikeno holds, although Timberlake supplies no evidence 
upon this point, is probably derived from the centrosome. Jahn (1904), 
too, finds that in swarm-spore formation in Stemonitis a body which oc- 
cupied the pole of an immediately preceding division and which he calls 
a centrosome, functions as a blepharoplast. In a later paper, however, 
Ikeno (1906) has recognized the possibility that blepharoplasts are not 
all homologous structures; suggesting that there may be “centrosomatic 
blepharoplasts”, including those of the myxomycetes, hepaticae, pteri- 
dophytes and gvmnosperms ; “plasmodermal blepharoplasts”, occurring 
in Chara and some chlorophyceae ; and “karyoblepharoplasts”, as vet 
known onlv in certain flagellates. 
The question is evidentlv still open. A priori, the notion that the 
blepharoplast is phylogenetically a centrosome is plausible and attractive. 
It is certainly conceivable that the centrosome, formerly perhaps per- 
