1902] GAMETOPHYTES AND EMBRYO OF PODOCARPUS 103 
pollen grain (long known, of course), in the presence of two 
male prothallial cells, in the distribution and arrangement of the 
archegonia, in the reduction of the number of functional male 
nuclei to one (?), and in the penetration of the pollen-tube into 
the archegonium. The first three of these characters, at least, 
are of much taxonomic importance, as is shown by their con- 
stancy in the different groups. On the other hand, the struc- 
ture and manner of formation of the proembryo, where points 
of difference appear, although constant, so far as known in the 
Abieteae,’® are by no means so constant in other families, and 
are not of such value in classification. 
hen it is noted further that none of the characters of 
agreement mentioned are found in the Cupresseae, and few of 
them in any other conifers, it seems safe to conclude that in the 
Podocarpeae are to be found the nearest living relatives of the 
Abieteae. 
SUMMARY. 
\. The pollen grain contains two prothallial cells. 
__ 2. The second prothallial nucleus persists and is found later 
_ ithe tip of the pollen tube. 1t may divide amitotically. 
= ‘The mature pollen grain sometimes contains as many as 
‘nuclei, probably abnormally. | 
4. The pollen tube reaches the prothallium before the arche- _ 
ha i initials can be distinguished. It contains no starch. 
e — aes but one functional male cell formed. oe 
| eee : | MFC is no “ spongy” tissue around the macrospore. 
: ‘ie segs is furnished with a distinct epidermis- 
| i. . sy via regular cells which are modified for secretion. [ 
- One of q. prothallia were once found in the same ovule. 
em contained tracheids. nae ee 
_ % The archegonia vary from about seven to eleven, and all 
: “ ‘a sa ai and number of cells. Two large kinoplasmic 
wate interarchegonial development is referred to here, Many variations 
icropylar end of the prothallium. The neck varies 
