NOTICES OF BOOKS. 5l 
nurse and mother’ of the simplest 4/72, by the decay of whose 
fronds, (the invisible detritus being, perhaps, carried down with the 
melting snow,) a vegetable soil is furnished for those very Lichens 
which claim to occupy a prior station in the scale of existence. 
Whether the Protococcus of the snow be justly entitled to its name, 
or whether it is in like manner dependent on a yet earlier organism, 
it is impossible for us to decide: with our present amount of know- 
ledge, it appears to be the simplest of all vegetables ; and still, from 
its microscopic minuteness, we can trace upwards, in one unbroken 
chain of affinity, a series of analogous structures, gradually be- 
coming more complex, which link it in close relationship with the 
great Alge of the Southern Ocean, one of whose enormous fronds 
is more than a sufficient load for a man. The Protococcus, as- 
suredly, bears a striking resemblance, in structure and aspect, to 
the spore of one of the larger 4/77 ; and a hasty observer might 
pronounce it to be nothing else than a spore, arrested in its pro- 
gress by the ungenial soil and climate around it, but which, if 
placed in favourable circumstances, would gradually advance to a 
higher organization. Such a conclusion is not warranted by 
facts; for, though this plant was originally detected on the snow 
of the Alps, and afterwards observed in similar situations on the 
Andes, and within the Polar circle, it is yet by no means confined 
to snow: it occurs on rocks, down to nearly the level of the - 
sea, in a great variety of climates, and still preserves, throughout 
this wide discrepancy of * modifying causes,’ an identity of struc- — 
ture, becoming neither more nor less complex. It is excessively 
common in Europe, on the surface of rocks, (not exclusively on 
limestone, as has been affirmed,) wherever water frequently lodges — 
in depressions ; and I have seen it in such situations, at the Cape 2 
of Good Hope, where snow never lies, and very rarely falls. With- —— 
out presuming, therefore, to assert that the Protococcus admits of 
no higher development, we may be allowed to remark that our 
present knowledge of this humble plant invalidates, in nought, 
the fundamental law of organic nature; viz.,—that every living _ 
thing, plant or animal, has received, at its creation, a certain charter _ 
of ede within which it and its progeny may range, but which 
