ON THE SEXUAL ORGANS OF THE CYCADACEE. 103 
pollen can penetrate into the inverted ovule, from their opening, instead 
of being directed to the periphery, being applied against the axis of 
the cone. The difficulty increases when it happens, as in certain spe- 
cies of Dioon and Encephalartos, that the entire cone is covered with 
a compact pubescence,—is as if it were enveloped in a tissue of wool. 
Nature, however, finds its way, as is proved by the numerous seeds 
provided with an embryo whieh the ripe cone exhibits, as well as in 
Conifers, where it is common to see in our climate pollen fixed on the 
nucleus. The groups of plants whose origin extends to the palæozoic 
time, show themselves therefore to be independent of insects. They 
remain now as at the earliest period of their existence, and we see that 
nature adopts other means to bring the microspores into contact with 
the inacrospores. 
Note by the Translator.—In page 74, line 30, the last clause of the 
. sentence should have been rather more correctly rendered, ** It would 
be, besides, a structure of which I know no other analogue." 
The meaning of the whole passage admits of being made clearer by 
a reference to Oudemans' view of the matter which Miquel controverts. 
The former writer states that “the epidermis of the entire ovule" (in- 
cluding its coat) ** penetrates into the micropyliferous tube" (exostome), 
* and descends at first vertically, then obliquely, to the foot of the 
conical protuberance, to the summit of which it is reflected so as to 
cover it exactly, with the exception of its extremity (* Archives Néer- 
landaises,” ii. 1867). 
Miquel considers that the epidermis of the coat, and the epithelium 
of the nucleus are distinct structures, although intimately united up 
to the point, where the cone of the nucleus detaches itself from the 
coat,—W 
EXPLICATIO TABULARUM. 
(Si nihil adnotatum, figuras nat. magn. delineatas intelligas.) 
Tas. XCI. 
Fig. 1. Pars eS ncaa prions —— secta, vasorum fas- 
ciculos et canales gummifer nstra , pars nucle i libera ; b, carum 
ii al ie te. 
Fig. 2. 2. Ejusdem ovulum, amnii cavitate jam mte se 
Fig. 3-4. Eadem auctiora, nuclei textu ; c, jam partim repulso. 
Fig. 5. Idem provectius; a, integumen nti stratum peres molle ; b, stratum 
4 
