HOOKER ON WELWITSCHIA. 
211 
In this notice we have entirely passed over the interesting 
phenomena of the embryogeny of Welwitsclnia , which is largely 
illustrated by Dr. Hooker. These correspond in the main with 
what has been observed in Gymnosperms. Welwitschia presents, how¬ 
ever, one very remarkable and exceptional feature in the secondary 
embryo-sacs, which grow out of the primary embryo-sac into the 
tissue of the nucleus above, where they encounter the descending 
pollen-tubes and are fertilised. Perhaps at some future time we 
may return to a discussion of the embryogeny of this plant, in con¬ 
nection with that of Gnetum and other genera, not Gymnospermous, 
which present some points of analogy with them. 
In conclusion, we must express our gratification that it has fallen 
to the lot of a botanist, so distinguished by experience, and great 
philosophical attainment, as Dr. Hooker, to unfold this very extra¬ 
ordinary object the first to our view. Ho time has been lost in pre¬ 
senting to the scientific world the memoir which has been so 
anxiously awaited. The execution of it bears ample testimony to 
the faithful endeavour of its author, to render it worthy in every 
way of the rare occasion. We must not omit either to express our 
high satisfaction with the admirable execution, by Mr. Pitch, of the 
numerous plates which illustrate this memoir. 
XVI.— The Antiquity oe Man from Geological Evidences ; 
with Remarks on theories of the Origin of Species and 
Variation. By Sir Charles Lyell, E.R.S. 8vo. London: 
Murray, 1863. 
Until the great antiquity of this Earth was admitted, Geology could 
hardly be treated as a science, and as long as we endeavoured to 
compress the history of Man into the narrow limits of six thousand 
years, the atoms of truth which we possessed were unable, for want 
of space, to arrange themselves in their proper order. Realizing the 
difficulty, Zoologists, more or less boldly, hinted at a diversity 
of origin ; Philologists took refuge in the Tower of Babel; and 
Archaeologists abandoned in despair all hope of ever reconstructing 
the past. Of late years, however, science has made immense progress, 
and although with singular disregard for truth, and scanty reverence 
for the book which we profess to venerate above all others, we still 
place at the commencement of our Bibles Archbishop Usher’s 
unfortunate estimate, 4001 b.c., yet there is perhaps no educated man 
in this country who is not well aware that the antiquity of the world 
is to be measured, not by thousands, but by millions of years. With¬ 
out claiming for ourselves the gift of prophecy, we doubt not that 
the great antiquity of Man will ere long be as generally recognised. 
We speak thus confidently, because, in the first place, we are our- 
individually covered by a tliin film (of cellulose ?) explains why they were not pre¬ 
viously understood, since this film protects them from the action of dilute hydro¬ 
chloric acid. 
P 2 
