1908] BURLINGAME—PODOCARPUS 169 
time starch may or may not be present; later it becomes abundant 
and occurs in relatively large grains (figs. 30, 31). The wall has a 
thick exine much roughened on the outer surface and a distinct 
intine. The spore coat is usually much thinner on the side away 
from the point where the prothallial cells will later lie. The external 
appearance of the pollen grain bears a considerable resemblance to~ 
that of Pinus, except that it is smaller, rarely reaching more than 
35 # in the greatest diameter (exclusive of the wings). 
The microspore nucleus is large (fig. 18) and contains apparently 
two sorts of material. There is a more deeply staining substance 
distributed in irregular masses through a very fine ground substance. 
As the nucleus prepares for division, the amount and density of the 
more deeply staining substance increases in amount, assumes a more 
definitely reticulated structure, and finally passes into a rather thick 
and comparatively short spirem (fig. 29). This spirem breaks up 
into the chromosomes (fig. 28), which often still show the distinct 
segmentation into lighter and darker segments that has already been 
referred to in discussing the sporogenous tissue. This segmentation 
1s not always found in the chromosomes or even in the spirem. It 
might be supposed that the different appearance is due to differ- 
ences in the depth of stain, but this does not seem to.be true. 
The chromosomes are rather long and considerably twisted at the 
Metaphase, but in dividing and passing to the poles they apparently 
shorten up (fig. 31). What has been said of the first division applies 
equally well to the next, so far as the few mitoses observed show. 
One or two prothallial cells are cut off and then the antheridial 
Initial divides to produce the tube nucleus and the primary spermato- 
senous cell (fig. 32). In P. nivalis two primary prothallial cells, 
which do not subsequently divide, seem to be the rule, though one 
€xample of the division of the first prothallial was observed. The 
pollen in the same sporangium varies in the stage of development 
from microspores to the stage shown in fig. 32. These sporangia 
Were, in some cases at least, shedding their spores. 
In P. totarra Hallii one primary prothallial cell may be cut off, 
alter hich the free nucleus divides to form the primary spermatogenous 
Cell and the tube nucleus (fig. 21); or two primary prothallial cells 
may be cut off before the tube nucleus is separated from the primary 
