DR. J. D. HOOKER ON WELWITSCHIA. 31 
tissue in its styliform prolongation; unlike a carpel, it rises symmetrically round the 
nucleus, and in the hermaphrodite flower presents a symmetrical terminal dise, and it 
ceases to grow long before the maturation of the seed; and still more unlike a carpel, 
it is carried up with the growing seed, till its base is on the apex of the latter. In all 
these respects, except in the long styliform process, it accords with the inner ovular inte- 
gument of phznogamic plants, which, indeed, have not unfrequently tubular orifices 
prolonged beyond the nucleus, though not so far as that of Gnetacee. 
To these considerations must be added that of the exterior integument of Gnetum, 
which is as clearly an appendage of the ovule as the interior, but which must be con- 
sidered to be either staminal or a production of the disc, if the inner coat is considered as 
carpellary. 
Lastly, ovular integuments are singularly uniform in their structural anatomy, which 
seldom deviates from one common type; and in the normal condition of the ovule, it is 
devoid of appendages, or of other external or internal characters whereby those of allied 
species, or even genera and orders, can be distinguished from one another. I am not 
aware that a single natural family or genus of Angiosperms presents any structural 
peculiarity of the outer or inner coats of its ovule: on the other hand, the carpel is, of 
all the floral whorls, one of the most various; and, as often happens with other organs, 
the more reduced it is, and the more it deviates from the foliar type, the more liable it 
is to vary : whence it is all but inconceivable that the ovular integument of Gymno- 
sperms should be carpellary, and yet constant in structure. 
If, then, we were to assume the ovular integument of Gymnosperms to be carpellary, 
we must admit, first, that it has neither the form, structure, nor functions of an angio- 
spermous carpel; secondly, that it has those of an angiospermous ovular coat; and 
thirdly, that while the carpel is a singularly varying organ in the genera and even species 
of Angiosperms, it is a singularly uniform one in those of Gymnosperms. 
Fertilization and Embryogeny. Seed. 
Fertilization,.—l know nothing definitely of the epoch at which fertilization normally 
takes place in Welwitschia, nor indeed of its flowering and fruiting seasons. Dr. Welwitsch 
gathered young male flowers, together with nearly mature fruit, in September ; and the 
fine specimens last sent by Mr. Monteiro, on which are old male cones, must have been 
gathered at about the same period of the year. Mr. Baines's sketch, again, which re- 
presents ripe cones, bears date May 10th. 
It is reasonable to suppose that impregnation is effected by insect agency, and that 
when the pollen is ready for transport the female cones are still very small, and the 
nucleus of their ovules is neither covered by the ovular integument nor by the peri- 
anth. At such a period the staminate and female cones are probably of about the 
same size, and their scales more patent than they afterwards are in the female. Such an 
arrangement, indeed, appears necessary ; for it is obvious that, after the ovular integu- 
ment has assumed its styliform shape (which is long antecedent to any change taking 
place in the nucleus), it would be extremely difficult to introduce a single grain of pollen 
by any conceivable means to the apex of the nucleus, and impossible to convey there the 
eurem PR m 
Mr we Ak MERI E cl 
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