12 BOTANICAL GAZETTE [JULY 
The sperm cells are now mature, and fertilization almost 
immediately takes place. I think it probable that the sperm 
cells do not round themselves off completely until after the 
bursting of the pollen tube, for although sometimes separated as 
much as a quarter of their diameter from each other, I have never 
seen them while still in the tube without a flat face on the inner 
side. This remarkably complex structure of the sperm cell dis- 
tinguishes Taxodium from any phanerogam hitherto described, 
with the exception of Ginkgo and the cycads. 
Recent work on the conifers, which in the structure of the 
male gametophyte approach Taxodium, gives very little detail 
as to the structure of the sperm cells. In Taxus Jager (’99) 
mentions radial striae in the periphery of both the sperm cell 
and its smaller, functionless sister cell, but gives no further 
details of the protoplasmic structure. Arnoldi (’98) says that 
in Cephalotaxus the protoplasm of the sperm cells, which are 
here of equal size, is densest around the nucleus. In his work 
on Sequoia (’99) he gives no details of the protoplasmic struc- 
ture of the sperm cells, but says they resemble those of the 
Cupresseae. Blackman (’98) makes some interesting observa- 
tions on the sperm cells of Pinus stlvestris. Hesays: “It cannot 
be doubted that cytoplasm also passes over into the oosphere, 
for each generative nucleus in the pollen tube is clearly sur- 
rounded by its own layer of cytoplasm, as can be observed in 
the stage when the tube is already in contact with the oosphere.” 
Also, “it may here be noticed that small bodies staining deeply 
with fuchsin S may be observed in the generative cell proto- 
plasm.’ These, he says, resemble leucoplasts. ‘If leucoplasts 
are really present in the cytoplasm belonging to the generative 
cells, the general view that the male cell brings over no plastids 
to the egg appears to be directly contradicted.’’ This is the 
only mention I have seen made of a distinctive protoplasm 
belonging to the male cells in any of the Abieteae. 
- Neither Belajeff (’91,’93) nor Strasburger (’79, ’84) describe 
the structure of the sperm cells of the Cupresseae in detail, but 
in gross structure they seem almost identical with those of 
Taxodium. Strasburger (°84) says that the pollen tube of Juni- 
