1909] SAXTON--WIDDRINGTONIA CUPRESSOIDES 173 
_ thing beyond the fact that they occur in a lateral group (or possibly 
‘more than one group). The formation of the multinucleate prothal 
lial cells has already been described. 
Sufficient evidence has been obtained 
to indicate that the development in 
Callitris is essentially similar to that 
of Widdringtonia. 
DISCUSSION 
I 
ii] 
With the exception of GoEBEL’s 
- (16) figure of Tetraclinis (Callitris 
_ quadrivalvis) and CoKER’s (8) state- 
ment about the pollen grain of Cal- 
: litris, I am aware of no contribution 
_ tothe knowledge of the gametophytes 
in the Actinostrobeae. As shown by 
MAsTERs (26), there is a very close 
_ agreement between the four genera of 
_ this section of the Cupressineae in 
sporophyte characters, and the present 
investigation shows that the section is much more clearly differen- 
tiated from other Cupressineae in the gametophyte than in the sporo- 
phyte characters. Especially is this the case in the female gametophyte, 
__where the peculiar position of the archegonia and the persistently 
_ multinucleate prothallus constitute a sharp distinction from typical 
_ Cupressineae. On the other hand, the position of the archegonia is 
< Similar to that found in Sequoia, and I hesitate to emphasize the 
7 differences in structure of the archegonia, as described above, until 
q the development has been more closely followed. It has already — 
_ been suggested that the Cupressineae have been derived from the 
. Sequoiaceae, and it is quite possible that the Actinostrobeae constitute 
the connecting link between the two tribes. : 
It is just possible, however, that the developmental details may 
have a wider significance than this in indicating an approach to on 
_ conditions met with in the Gnetales. If the apparent absence of 
3 neck cells in the deep-seated archegonia is confirmed, a comparison 1s 
_ at once suggested with the multinucleate prothallial tubes of Tumboa 
By 
“eS 
2 
= 
Fic. 3.—Tip of pollen tube of 
Callitris verrucosa. X77°- 
Ps 
