592 
Saxton. — Contributions to the 
in any of the three that failure to develop in the usual way is due to injury. 
As mentioned above, the suggestion has been made that cultural conditions 
are responsible for this peculiarity, but the tree from which my collections 
were made was growing in the open in a climate not very dissimilar to 
that of its native land, and such a suggestion does not seem adequate in 
this case. 
It is also interesting that where no apical archegonia occur, the apex 
of the prothallus remains truncate, and never becomes pointed as it does in 
the Callitroi'deae. 
Several prothalli were also sectioned which contained no archegonia 
at all, though otherwise they appeared perfectly healthy. Juel (21) also 
mentions the entire absence of archegonia in some of the material examined 
by him. In Widdringtonia sterile prothalli are also fairly common, and 
they have been found occasionally in other genera. It is not unlikely that 
this fact may be of some significance as indicating a certain degree of 
instability in the development of the gametophyte. 
The archegonia of Tetraclinis , whether apical or lateral, are never 
deep-seated in the sense of being derived from cells which are not superficial, 
but, as in related genera, become rather deeply sunk through the upgrowth 
of the surrounding tissue. This surrounding tissue impinges on the pollen- 
tube or tubes, and after fertilization, when the tubes break down, or at 
a corresponding time if no pollen-tube is present, the overarching cells 
meet over the archegonial complex. It seems certain that there can 
be no direct phylogenetic connexion between archegonia thus cut off 
from the exterior of the prothallus and those which are deep-seated from 
the first, any more than between a gymnospermous cone in which the 
scales meet and enclose the ovules and an angiospermous ovary which 
is enclosed ab initio. Nevertheless it would be very difficult, if late 
stages only were available, to distinguish between the two, and it seems 
probable to the writer that certain cases where deep-seated archegonia 
have been reported on rather inadequate evidence might be explained in 
this way. 4 
The dates given in the description of figures, corresponding to 
the dates of collection of different stages, do not suffice to fix the 
time which elapses between pollination and fertilization. Pollination 
occurred in the oldest ovules seen about April so, but the majority were 
certainly pollinated later, probably up to June 1 or a little after. At 
each collection the largest and oldest cones available were gathered, so 
that those ovules in which post-fertilization stages were first found (on 
September 2) were not pollinated at the same time as those of the 
earlier collections, but probably about a month later. Consequently the 
actual time which elapses between pollination and fertilization is from 
3 to 3J months. 
