5§2 
Saxton. — Contributions to the 
before the orange, with the sections mounted in water . Under these con- 
ditions what can otherwise only be seen with difficulty becomes entirely 
obvious. I have on several occasions (in fact each time cones have been 
fixed for stages of microsporogenesis) teased out fresh material in acetic 
methyl green ; in this way it can be most clearly shown that the spores lie 
freely inside the thin wall of the mother-cell. Fig. 24 is drawn from such 
fresh material (to a smaller scale than the other figures). I think there can 
be no doubt whatever that in Tetraclinis the mother-cell does not at any 
time become partitioned. 
It may be of interest to review the situation in other Gymnosperms in 
regard to this point. In the Cycads investigated (Juranyi (22), Treub (56), 
and Smith (50)), and in Ginkgo (Sprecher (51)), the mother-cell is chambered, 
the partition walls being thick and persistent. In regard to Ginkgo Sprecher 
remarks : c Chaque cellule fille 011 grain de pollen (microspore) aura sa propre 
membrane, puisque si on ecrase un tetrasporange, les microspores s’en 
echappent et laissent la membrane de la cellule mere (Fig. 182, get h ).’ 
The figures to which he refers show the partitioned mother-cell with thick 
walls, very similar to those of Cycads. 
In Pinus , according to Miss Ferguson (17), the mother-cell is partitioned 
in a somewhat similar manner. In Araucaria , Burlingame (5) leads one to 
suppose that the cell is not partitioned, but neither his description nor his 
figures are explicit on this point. In Thuja } Land’s (24) figures imply an 
unpartitioned mother-cell, as is also claimed for Juniper us ^ as mentioned 
above, by Noren (37), with whose results Nichols (36) is not in agreement. 
In Cunninghamia , Miyake (32) reports a chambered mother-cell, but his 
account appears to suggest a slightly different type to that found in 
other genera. In Torreya , Robertson’s (42) figures imply an absence of 
chambering. The writer has examined three other genera of Conifers in 
regard to this point, of which two, Actinostrobus (47) and Cupressus, showed 
the spores free in the mother-cell, while the third, Callitris , showed thick 
partition walls, more like those figured in Gnetum africanum (see below) 
than the figures of any other genus of Conifers. 
In the Gnetales, Ephedra (Land (25)) and Welwitschia (Pearson (39)) are 
not chambered, while Gnetum africanum and G. scandens (Pearson (41)) show 
thick partition walls, probably of a mucilaginous nature, though in other 
species of the genus the mother-cells are said not to be chambered. 
It is obvious that if all, or even the large majority, of these observa- 
tions are accepted as correct, then the character is one which cannot, 
on any scheme of Gymnosperm classification, be of any phylogenetic 
importance. 
Shortly after the formation of the microspores, the mother-cell wall 
degenerates and disappears entirely, and the wall of the young microspore 
begins to thicken. Very soon two layers can be recognized in the wall 
