13 
Embryo of Cephalotaxus drupacea . 
the tube had been discharged into one of the archegonial chambers before 
the neck-cells had been reached. Whether this early discharge of the tube 
contents is normal it is difficult to say. It may be due to the bursting of 
the tube by the fixing fluids, as the tip at this time has all the appearance 
of being under considerable osmotic pressure. In many cases examined the 
tip of the tube was carried between the neck-cells and into the archegonium 
before its contents were liberated. Fig. 25 shows the swollen end of the 
pollen-tube within the archegonium, and its contents are apparently still 
intact. As the tip of the tube approaches the neck-cells, the two sperm- 
nuclei may be separated from each other for a very short distance, but 
quite as frequently they cling close together until the interior of the 
archegonium has been reached. In Fig. 27 the tip of the pollen-tube is 
represented just outside the neck-cell; there is a space between the two 
sperm-nuclei, and these latter appear to be spherical in form. Arnoldi’s 
( 00) description of fertilization in Cephalotaxus Fortunei is very meagre, 
and from his figures it is difficult to make out just what happens during 
these stages. In several cases I was able to observe the two male nuclei, after 
entering the archegonium, to be still enveloped by the membrane of the 
body-cell, and frequently accompanied by the tube- and stalk-nuclei. From 
the disturbed condition of the cytoplasm above the egg-nucleus, the dis- 
charge of the tube contents and the migration of the sperm-nucleus towards 
that of the egg must take place with considerable force. This is clearly illus- 
trated in Figs. 28, 29, 30, and 31. 
It seems to be a common occurrence among the Coniferales for the 
entire contents of the pollen-tube to enter a single archegonium. According 
to Blackman (’98), Coulter and Chamberlain (’01), and Ferguson (’01), the 
pollen-tube itself does not enter the archegonium in Pinus , but its entire 
contents are forced between the neck-cells, and are later found in the cyto- 
plasm of the egg. Practically the same thing occurs in Taxodium , Picea , 
and Abies (Coker, ’03 ; Miyake, ’03), and a similar condition has recently 
been reported for Torreya taxifolia by Coulter and Land (’05). Exceptions 
to this are found in Torreya californica (Robertson, ’04) and in Sequoia 
(Lawson, ’04), where but a single sperm-nucleus enters the egg. From 
BelajefTs (’91) figures it seems that this may also be true for Taxus . In 
Cryptomeria (Lawson, ’04) a single male cell enters the archegonium. 
Among the Gymnosperms there seems to be a decided tendency to 
modify and reduce the structure of the male gametes. In the Cycads and 
Ginkgo we have the two free-swimming ciliated sperms. In the Cupressineae 
and Taxodineae there are two distinct male cells of equal size organized, and 
each is surrounded by an independent cell-wall. In Taxus , Podocarpus , and 
Torreya taxifolia there are two distinct male cells organized, but one of 
them is dwarfed and functionless and much smaller than the other. In the 
Abietineae, Cephalotaxus and Toi'reya californica , the two male gametes are 
