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PHYTOGENESIS. 241 My observations are much more limited with respect to the Cryptogamia; nevertheless, I found the cytoblasts in the sporidia of the Helvelloids, where, however, in consequence of their great transparency, they are only perceptible with a very strong magnifying power, and after the field has been much darkened. I have seen them in the large yellowish cells in the interior of the so-called anthers in Chara vulgaris. I also observed their development into cells in the sporules of Marchantia polymorpha, one of which, pushing the original wall of the sporule before it, forms the long capillary root (pl. I, figs. 18-20).

It is evident from the foregoing, that the cytoblast can never lie free in the interior of the cell, but is always enclosed in the cell-wall, and (so far as we can learn from the observation of those cytoblasts which are sufficiently large to allow of this very difficult investigation) in such a manner that the wall of the cell splits into two lamin, one of which passes exterior, and the other interior to the cytoblasts. That upon the inner side is generally the more delicate, and in most instances only gelatinous, and is also absorbed simultaneously with the cytoblast (figs. 8, 16, 21). In making a section, they are sometimes detached and scattered over the object, which might lead to the supposition that they lay free. It is probable also that subsequently, when absorption commences, they do become disengaged from their connexion with the cell-wall, and a slight touch may then be sufficient to move them from this position. The cell-wall is often considerably thickened in their neighbourhood, especially when they are somewhat globular; for instance, in the pollen-tube, which has become cellular in certain Orchidæe (figs. 16, 20).

Meyen, who should always be consulted with reference to anatomical questions, has endeavoured, in his Physiologie, vol. i, p. 45, &c., to establish the opinion, that the cell is formed of spiral fibres which lie closely one upon another, founding his view in a most ingenious manner upon his own beautiful observations on the relations of structure in fully-developed cells. My direct observation, which may easily be repeated by every one, shows, it is true, quite a different mode of formation; I must, however, bring the facts related by Meyen into unison with my discovery, in order not to permit an apparent contradiction to remain unresolved. 16