SE eee TE a Sy ae Le ie ere aa ee ON en ERE Yee Sane ee es oe 
IgIo] YOUNG—PODOCARPINEAE 83 
the generative cell does not divide until after the tube begins to 
grow. ‘The spindle in Phyllocladus is always more or less oblique, 
and results in the formation of a larger, more centrally placed body 
cell and a small stalk cell. 
In fig. 13 there is shown a peculiar but very common feature of the 
sections, the appearance as of an additional cell cut off from the body 
cell, but without a nucleus. This was noticed also in Podocarpus 
and Dacrydium. JEFFREY and CHRYSLER (7), in the case of Podo- 
carpus jerruginea and P. dacrydioides, describe a second lateral 
derivative cell and picture it with a nucleus. Brooks and STILEs (1) 
find the same thing in P. spinulosa, but it is not clear whether a 
nucleus is present or not. It is in these species that the most exten- 
sive prothallial tissue is found, consisting of eight cells. In the 
forms studied by BURLINGAME and myself, as well as in Dacrydium 
and Phyllocladus, no nucleus ever appears in the extra section of 
cytoplasm. The explanation is most easily found in Phyllocladus, 
where horizontal sections show that it is really only a part of the 
stalk cell. When we consider the shape of the generative cell and 
the position of the spindle in the division, it is evident that an oblique 
wall in such a dome-shaped structure could not help resulting in the 
partial encircling of one cell by the other. The situation can be most 
clearly shown by diagrams. A horizontal section in the position 
shown by the dotted line xy in fig. 15 would give a view such as is: 
outlined in fig. 16, while fig. 15 is the vertical section through the 
dotted line in fig. 16. Fig. 17 is an oblique section in about the 
position of the dotted line vw in fig. 15. In this case the second 
prothallial cell is seen encircled by the stalk cell. A change of focus 
brings into view the body and tube nuclei and a portion of one wing. 
If the stalk nucleus, as shown in fig. 16, were a little more elongated, 
it would be quite possible to obtain a vertical section in such a position 
as to show a small part of it on each side of the body cell. The appear- 
ance of JEFFREY and CHRyYSLER’s and of BrooKs and STILES’s 
figures of Podocarpus jerruginea, P. dacrydioides, and P. spinulosa 
suggests this as a possible explanation of the second lateral derivative. 
The fact has been noted that the division of the generative cell is 
anticlinal in Podocarpineae and Phyllocladus, and periclinal in other 
conifers and in cycads, the relative position in the latter having given 
