18 
REVIEWS. 
borne on different roots; but some individuals produce only one 
kind of pistil, or sporiferous organ ; and others , of the same species, produce 
constantly a sporiferous organ of a different kind. The spores developed 
in either system are equally capable of reproducing the species; and as the 
two kinds are always formed on different individual fronds, the idea 
of each species includes two individuals, and is not complete unless both 
are known. Hence the necessity, in forming our generic groups, to found 
them on the characters taken from both fronds. Perhaps the natural 
explanation of this double fructification is, to regard one form of the 
reproductive body as a true spore , supposed to be fertilized through the 
agency of an antheridium , and to consider the other as merely a gem- 
mule or bud, here reduced to a single cell, cast off by the parent plant, and 
capable of continuing an independent existence. If this be the true ex¬ 
planation of the phenomena, we have still to decide (and from analogy only, 
for evidence of fertilization is wanting) to which of these bodies we shall 
give the name of spore, and which we shall call gemmule. And here 
different botanists take different views, the positive evidence, as it seems to 
me, being nearly equal in favour of either. Having no new facts to bring 
forward, I shall not argue this question here, but adopt the name spores 
and tetraspores , for these reproductive cells respectively.” We regret that 
space will not allow us to follow Dr. Harvey through the rest of this most 
interesting portion of his memoir. In it he has adopted a classification, 
based on the structure of the sporiferous nuclei , similar to that followed 
by Professor J. G. Agardh, whose “ Species genera et or dines 
Algarum” (Lund., 1848, 1852) is highly and deservedly praised for 
accurate analysis, careful description, and original conception. We must 
now take our leave, for the present, of these contributions to the algology 
of the American coasts, which ably sustain the high character for 
scientific zeal and laborious research long awarded by his fellow-students 
to Professor Harvey. 
We understand that a similar devotion to science, as that which produced 
these volumes, has led their gifted author to explore other regions 
in search of his favourites; and that, probably, while these pages are 
passing through the press, he is algologising on the coasts of Australia. 
We most cordially wish every success to his labours, and hope that, on his 
return to his native land, their fruits may equal, if not surpass, those which 
are presented in the volumes we have been considering, as the result of his 
American trip. 
