164 BOTANICAL GAZETTE [MARCH 
the cavities formed by the breaking down of young sporogenous and 
adjacent tissue should become resin cavities in conifers is to be 
expected. 
It was only in the abortive sporangia of Torreya that stages were 
- found indicating the history of the sporangium up to the primary 
sporogenous cell stage. For example, from jig. g it seems evident 
that there was a single hypodermal archesporial cell, which at this 
stage had given rise to two layers of wall cells and a single primary 
sporogenous cell. In the mature sporangium there are three or four 
wall layers. The epidermis contains numerous stomata, and its 
cells become prominent and have thickened walls. The sporangia 
are bluntly four-angled from pressure, and the epidermal cells at 
the angles are much larger than elsewhere. 
MALE GAMETOPHYTE.—We secured no stages between the very 
young sporangium and the shedding of the pollen, which occurs late 
in March and early in April. Miss Roperrson (8) has observed 
the mother-cell stage and the formation of tetrads in T. californica. 
In germination the microspore of 7. taxifolia cuts off no prothallial 
cell, a feature common to all the Coniferales except Podocarpeae 
and Abieteae. After the first division the generative and tube cells 
are distinct and separated by a very delicate wall or membrane. 
The tube nucleus is sometimes spherical, but more often amoeboid 
(fig. 12). 
Early in April the binucleate pollen grains, rich in starch, wert 
found resting on the nucellus (fig. 19); and at the end of June micro- 
pyles were found full of pollen grains, most of which had sent out no 
tubes, but were still full of starch, nucleate, and apparently alive. 
As fertilization occurs about the middle of August, active pollen 
tubes occupy the sterile cap of the nucellus about four months, and 
their behavior is exceedingly variable. They may advance towards 
the embryo sac rapidly, reaching it at a very early stage, a5 early as 
June 21, when the endosperm consists of only sixteen to sixty-four 
parietally placed free nuclei (figs. 14 and 15); or they may advance 
slowly, being found at all stages of progress at the same date. They 
may advance so directly that the tube resembles a straight cleft 
through the nucellar tissue to the sac, or they may pursue a remar* 
ably devious course. In one case a tube passed directly half-way 
