Davis. — -Spore Formation in Derbesia. 1 1 
Ikeno (’98) for Cycas, Hi rase (’98) for Ginkgo , and Webber (’01) for Zamia 
agree in describing the blepharoplasts as arising de novo on opposite sides 
of the nucleus and at some distance from it, before the mitosis that precedes 
the differentiation of the sperm nuclei. The spindle of this mitosis is said 
to hold no relation to the two blepharoplasts which are far removed from 
its poles. Ikeno and Hirase have from the first held that the blepharoplast 
was an attractive sphere or centrosome, and Ikeno (’04) has more recently 
emphasized his views of the homology of the centrosome and blepharoplast 
of plants. Webber, however, laid stress on the striking fact that the 
blepharoplasts are independent of the spindle fibres of the last mitosis 
of spermatogenesis of Zamia , and are formed de novo at some distance 
from this nucleus, while it is in the resting condition, a developmental 
history which would not be expected of a centrosome-like structure. 
Ikeno (’03) has also reported centrosomes during the mitoses of spermato- 
genesis in Marchantia , stating that the centrosomes of the last mitosis 
become the blepharoplasts of the sperms. Miyake (’05) has not been able 
to confirm Ikeno’s conclusions respecting the presence of centrosomes during 
the mitoses of spermatogenesis. However, he finds a body at each spindle 
pole of the last mitosis of Marchantia and groups of granules similarly 
situated in Makinoa , and he considers these as likely to function as blepharo- 
plasts. Ikeno (’05) has replied to the criticisms of Miyake, but this discussion 
is not essential to the problem before us. 
The views of botanists respecting the origin and nature of the blepharo- 
plast are then at variance in fundamental points. Strasburger, Shaw, 
Webber, and Mottier hold that the blepharoplast is not a centrosome, 
but arises either in the plasma membrane or in the cytoplasm, independently 
of the nucleus. Belajeff, Ikeno, and Hirase believe it to be related to the 
centrosome. There are conflicting accounts of its history even in the same 
forms, and very little information concerning its origin even in the most 
favourable types, such as the cycads and Ginkgo. 
Let us now consider the history of the blepharoplast of Derbesia 
in relation to the confusion of views described above. The blepharoplast of 
Derbesia has clearly very important physiological relations to the nucleus. 
The granules that enter into its composition come from the surface of the 
nucleus and travel along a system of protoplasmic strands to the plasma 
membrane beneath which the blepharoplast is formed. Timberlake’s account 
of Hydrodictyon has many points of agreement with this history and offers 
substantial support, although the zoospores of that form are too small 
to trace the development of the blepharoplast as easily as may be done in 
Derbesia. This history for Derbesia does not accord at all with Strasburger’s 
view of the origin of the blepharoplasts in Oedogonium y Cladophora, , and 
Vaucheria from the plasma membrane, or the similar account of Mottier for 
Chara. I cannot but believe that a closer study of the development of the 
