GYMNOSPERMS. 145 
nucleus toward the periphery of the cell (Fig. 57, D, c). With fur- 
ther growth the generative cell with its nucleus becomes elliptical, their 
major axis lying parallel with the longitudinal axis of the tube. The 
two primordia of the blepharoplasts, which lay previously in-line 
parallel with the transverse axis of the tube, are now found in the ends 
.of the generative cell, About each there soon appear beautiful kino- 
plasmic radiations, giving them a most striking resemblance to centro- 
spheres with large centrosomes. Later in the period of development, 
or about the middle of August in Japan, the young blepharoplasts 
shift their position again, so that their earlier orientation in the gene- 
rative cell with respect to the axis of the pollen tube is resumed (Fig. 
57, E). The generative cell becomes spherical, and the kinoplasmic 
radiations are very conspicuous. 
From this time until the end of September, or about one and one- 
half months, few changes manifest themselves in the generative cell 
apart from an increase in size. This period in the development is, 
therefore, a period of growth, which corresponds to a similar period 
in the development of the archegonium, and at the end of which all 
elements have reached their maximum size (Fig. 57,E). The diameter 
of the generative cell, which contains dense cytoplasm, is about 0.14 
mm., and that of the nucleus is about 60 ». The primordia of the 
blepharoplasts have also increased considerably in size; they are about 
15 windiameter. Apart from the presence of one or more vacuoles, they 
are rather homogeneous massive bodies. . The kinoplasmic radiations 
are still beautifully developed; they seem to pass over gradually and 
insensibly into the alveolar structure of the cytoplasm. 
About the middle of September the tube nucleus begins to migrate 
toward the proximal end of the pollen tube, and, by the end of the 
month, this nucleus, the generative, stalk, and outer prothallial cells 
are all in the proximal end, which is capped by the exine of the spore. 
It may be mentioned here that the migration of the tube nucleus into 
the proximal end of the pollen tube seems to be a striking confirmation 
of the doctrine of Haberlandt, namely, that in a growing cel] the 
nucleus generally takes a position near the seat of constructive activity. 
Since the proximal end of the tube now grows toward the archegonium, 
and as growth at the distal end ceases, it is to be expected, in harmony 
with the theory of Haberlandt, that the nucleus which presides over 
this growth should move toward the region of that activity. Webber 
has observed the same behavior of the tube nucleus in Zama. 
The final processes which now take place in the male gametophyte 
have to do largely with the development of the two spermatozoids 
