Vegetative Cone. A remarkable difference in the mode of development of the punctum vegetationis occurs almost uniformly between Cryptogams and Phanerogams. In Cryptogams the whole of the cells of the primary meristem almost invariably owe their origin to a single mother-cell lying at the apex of the punctum vegetationis, and called the Apical Cell. In Phanerogams, on the other hand, without exception, there is no single apical cell of this character; even when a cell lies at the apex, it is not, as in the former case, distinguished by its greater size, nor can it be recognised as the single original mother-cell of all the cells of the primary meristem.

We have attempted to give here only the merest outline of the constitution of the cell and of tissues. For the further elucidation of the subject we must refer our readers to the more modern text-books of botany, especially Prof. Sachs's Lehrbuch," an English edition of which is about to be published by the Clarendon Press, Oxford.

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THE CHANNEL TUNNEL.

BY W. TOPLEY, F.G.S., Assoc. INST. C.E.,

GEOLOGICAL SURVEY OF ENGLAND.

[PLATE CXIV.]

HERE have not been wanting men who held that, in some

notwithstanding all the triumphs of modern science and civilisation. In one particular, at least, the primitive inhabitants of Western Europe are to be envied. The men who waged war with the ancient British lion, the cave bear, or the hairy mammoth, had no need to cross the sea if they wished to extend their hunting-grounds far to the east. Similarly, the old inhabitant of central France could as easily, if he so chose, follow the hippopotamus in his migrations to the Thames. For, in those old times-as there is good reason for believing-a band of Chalk extended across what is now the Straits of Dover, and the area now known as the British Isles was united to the continent of Europe.

How long ago it may be since this old "bridge" was broken we cannot know. Probably no Englishman will regret that the bridge was broken, and few will wish it wholly restored. But, certainly, most of those who have occasion to cross the Channel will wish that we could again have the personal convenience of continuous land communication, without the political disadvantages which such communication would involve. Modern civil engineering has resolved to attack this problem. Some of the proposals for accomplishing it we will presently examine.

The plans which have been advanced for lessening the inconveniences of the Channel passage have taken various shapes. It would be impossible, within the limits of a short article, to go over them all; we will therefore confine our attention to those schemes which propose to solve the difficulty by constructing a submarine tunnel. Proposals not falling under this head are various enough. Embankments, bridges, and tubes, in one form or other, have been proposed; but the scheme which seems to have found most favour, with engineers and with the public, is that of a tunnel.

The idea of constructing a tunnel between England and France seems to have originated with a French engineer, M.