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AND AFFINITIES OF STEPHANOSPERMUM. 379 
and adapted to freeing antherozoids if the necessity arose. In old-looking and probably 
much macerated pollen-grains, such as are occasionally to be observed, the whole system 
of internal walls appears to have broken down, leaving (in the rarest instanees) what 
may possibly be small complexes of secondary cells. It is possible that here we have 
an indication of the formation of antherozoid mother-cells in considerable number 
in each. However, adequate data are lacking for a satisfactory hypothesis in this 
species. The subject will be alluded to again on p. 385, when dealing with Stephano- 
spermum caryoides. m 
Renault has concluded that the pollen in this, as in other cases, underwent con- 
siderable growth in the pollen-chamber where it matured. He compared the dimensions 
of Stephanospermum pollen scattered in the matrix with that in the pollen-chamber, and 
infers a growth of about one third *. 
As already stated, I have found numerous abortive grains present with the normal 
large grains in the pollen-chamber, and also, in certain cases, grains that have remained 
trapped in the micropyle. 
I append a summary of the dimensions of these various grains, which wholly corrobo- 
rates the view of M. Renault :— 
Pollen-chamber shown in 
Fig.3 . . . . Average length of three normal grains in the pollen-chamber . 180 p. 
Fig.8 . .. . Ditto oF tive abortive grams < : s v ; kd! wo RN 
Fig.6 . . . . Average length of three normal grains in the sites chamber . 150 y. 
Fig.6 . . . ev Ditto of five trapped in the miceropyle . os i u « 1s « . OG 
Fig.2 . . . . Deneth of largest grain. : s 5. 4 OA eL MM 
Fig.15. ... .. Dengthof the large grain ng ods 4. 4e E n ME 
General average of length of pollen-grains of this species scattered in the matrix . . . 604. 
(2) Pollen of Stephanospermum caryoides. 
In the pollen-chamber of this seed eight pollen-grains or portions of pollen-grains 
have been found. They occur either attached to the lining of the chamber or very 
near to it. For convenience, the positions of seven of these bodies are represented in 
text-fig. 2, p. 380 (p.-p.5), as though they all occurred in a single section. They are 
really present in three sections, but for convenience of reference they are projected on to 
one plane. The eighth grain, which shows nothing, has not been included. The whole 
of these bodies appears to belong to one sort of pollen, a conclusion based on the dimen- 
sions of the various parts and on the nature of the sculpturings of the exospore ; and as 
they show various Cevelopmental stages, and none of them is abortive, it is exceedingly 
probable that these grains really belong to the seed in the pollen-chamber of which they 
occur T. 
Of the bodies mentioned, two are complete pollen-grains; the rest, fragments 
apparently in various phases of development. p. and p.? (text-fig. 2) are pollen-grains ; 
p-), p, p-^, p^, and p.? isolated internal cells of pollen-grains. 
* ' Cours de botanique fossile, vol. iv. p. 185. 
T Unfortunately a second specimen is not available to test this assumption. 
312 
