18 REVIEWS. 



borno 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. 



