OF THE EMBRYOS IN THE SEEDS OF CONIFERiE. 569
the extreme slowness in the process of maturation, con- joined with the considerable size of their seeds, and also from the striking peculiarity already noticed, were probably the best adapted for an investigation into the origin and successive changes of the vegetable em])ryo.
With this view^ chiefly I connncnccd in the present summer (1834) a series of observations, intending to follow them np from the period w4ien the enlargement of the im- pregnated cone begins to take place, to its complete ma- turity at the end of the second or beginning of the third year.
Pinus syhestris was selected for this purpose, corres- ponding observations being also made on other species, particularly Pinaster and Sfrobi/s ; and although the inves- tigation is necessarily incomplete, the facts already ascer- tained appear to me of sufficient importance to be sub- mitted to physiological botanists.
In an essay on the organs and mode of fecundation in OrcJiidecd and Asclepiadece, published in 1S31, I have given some account of the earliest changes observable in the impregnated ovulum of the former family; and in noticing the jointed thread, or single series of cells by which the embryo is suspended, I remarked that the terminating cell or joint of this thread is probably the original state of what afterwards, from enlargement, subdivision of its cavity, and deposition of granular matter in its cells, becomes the more manifest rudiment of the future embryo.
I had not indeed actually seen this joint in its supposed earliest state ; the following observations on Pinus, how- ever, will perhaps be considered as giving additional pro- bability to the conjecture.
But before entering on my account of the origin and de- velopment of the embryo in Pinus, I shall state briefly the still earlier changes conse(|uent to impregnation that take phice in this genus ; not only with the view of rendering the account of the embryo itself more readily intelligible, but also in confirmation of the opinion formerly advanced on the nature of the female organ in Conifer ce and Cycadac.
The first and most evident change observable is the pro-
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