1898] CURRENT LITERATURE 369 
turns in the cytoplasm, in this process becoming drawn out into a spiral band 
along the edges of which cilia are developed. The antherozoids escape 
from the mother cell and swim freely in the liquid contained in the pollen 
chamber. According to Webber the-antherozoids in Zamia are themselves 
ciliated mother cells and the pollen chamber contains air only. 
Antherozoids in gymnosperms have now been described by Hirasé™ in 
Gingko biloba, by Ikeno” in Cycas revoluta and by Webber® in Zamia integri- 
folia. All three find a pair of spherical bodies in the cell which is to give 
rise to the two antherozoids. Hirasé and Ikeno agree in calling these bodies 
centrosomes but Webber not believing that they are centrosomes calls them 
centrosome-like bodies, and later proposes the term blepha t ies 
probably homologous with these centrosomes or blepharoplasts have recently 
been described by Belajeff and Shaw in several pteridophytes ile Gingko» 
pollen grain structures they present considerable variation in details, espe- 
cially in the history of the body cell and the formation of the antherozoid. 
These investigations have added so much to the evidence accumulating 
from other sources, that Engler has removed Gingko from the conifers and put 
it by itself in the Gingkoales, a group coordinate with cycads, conifers and 
gnetums.—Cuas, J. CHAMBERLAIN, 
NUCLEAR DIVISION IN SPIROGYRA has been studied for a long time and 
the most contradictory results have been obtained, especially in regard to the 
chemical nature of the nucleolus and its réle in karyokinesis. Some claim 
that the nucleolus is fully analogous with that of the higher plants, while 
others think it very different both in chemical composition and its réle in 
karyokinesis. Some believe that the nuclear plate is formed exclusively at 
the expense of the chromatic network of the nucleus, others that it comes 
from the nucleolus and still others that it is formed partly from the nuclear 
network and partly from the nucleolus. The origin of achromatic parts is 
also in dispute, some claiming a cytoplasmic origin, others a nuclear origin 
and still others a mixed origin partly cytoplasmic and partly nuclear. 
L. Mitzkewitsch™ has recently presented a thorough discussion of pre- 
_Vious literature and added a most important contribution to the subject. 
The most modern killing and fixing agents were employed. After washing 
in water, alcohol was added to the water drop by drop at intervals of a minute 
or more until the material was dehydrated. The transfer from alcohol to 
xylol and from xylol to paraffin was equally gradual. 
The investigations deal almost exclusively with the nucleolus and the 
* Loc. cit. and Bot. Cent. 69 : 33-35. 1897. 
* Flora 85 : 1. ce and Bot. Centralbl. 
73 Bot. Gaz 451-459 and 24: 16-22, 225-235. 
4 Ueber die Secathatlens bei Spirogyra. Flora us mie “124. 1898. 
