1903] GAMETOPHYTES AND EMBRYO OF TAXODIUM 17 
Chamberlain (’ 01) also report four potential megaspores in Pinus 
Laricio, and Shaw ( 96) has given the number as four in Sequoia. 
Almost nothing is known of the divisions of the megaspore 
mother-cell in the Cupresseae beyond Strasburger’s. remark that 
in Thuja the origin of the prothallium is essentially as in Taxus. 
THE LARGE-CELLED TISSUE OR TAPETUM. 
The cells immediately adjoining the megaspore mother-cell, 
as before stated, contain starch (jig. 39). After the megaspore 
is formed and begins to increase in size, the number of these 
dense, starch-containing, much enlarged cells is found to be 
greater (jig. 45). In fig. 39 the transition between the starch- 
containing cells and the ordinary tissue around them is not very 
abrupt, but in jig. 45 the boundary between the two has become 
distinctly marked. The larger cells are in close contact, their cell 
walls are intact, and their nuclei are large and apparently per- 
fectly normal. Indeed, one of them is dividing mitotically, and 
they are not infrequently found dividing at this stage. Fig. 46 
shows such a cell in division. The spindle is placed centrally in 
the cell—not at one end, as in the division of the spore mother- 
cell—and in one case a cell-plate is being formed. The chro- 
mMosomes were not counted, but the number is much more than 
twelve. The division seems to be an ordinary typical one. The 
cells immediately beyond the large-celled tissues are distinctly 
flattened and seem to be crushed by the cells within. On the 
lower side the nuclei of the nucellar tissue are frequently small, 
deeply stained in safranin, and apparently going to pieces. In 
One case at about this stage the nuclei in this position had 
entirely disappeared for a distance of several layers beyond the 
normal large-celled tissue. ig. 47 shows the large-celled tissue 
ata later stage. It has increased greatly in amount and the 
cells, which are now slightly separated from each other, are much 
more numerous. They retain the characters mentioned above for 
a younger stage. 
The nucellar cells bordering on this tissue now show unmis- 
takable signs of disorganization. They are completely crushed 
and broken up and are as strongly distinct from the large-celled 
