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POPULAR SCIENCE REVIEW. 
the same obtains with the remainder. We can, with more and more cer- 
tainty, echo the aphorism of Harvey, “ Omne vivum ex ovo." The pheno- 
mena of geneagenesis mask, but do not alter, the principle of this great 
truth. Buds are the products of pre-existing germs, — secondary germs, in 
fact ; and a gemmiparous reproduction suffices not to perpetuate the species, 
for at the end of a certain time reproduction by an egg becomes absolutely 
necessary. This alone is a function of the first order, to which gem- 
mation is only subordinate. 
In the latter part of his work, M. de Q,uatrefages combats the opinion 
of Professor Owen, of whom he speaks with the greatest respect, on the 
subject of parthenogenesis, and offers his own views of these phenomena ; 
pointing out that, like multiplication by buds, or by suckers, natural or 
artificial, or by alternate generation, all of which he believes to be mani- 
festations of one and the same grand phenomenon, so also parthenogenesis, 
or virginal reproduction, is but a particular case of geneagenesis, and, 
therefore, comes in the same category as those before mentioned. 
The work of M. de Quatrefages abounds with original views and clear 
expositions of complicated and obscure phenomena, which he has brought 
into an ingenious and useful connection. We look upon it as the best 
that has appeared upon the difficult subject of which it treats, and should 
like to see it laid before the public in an English dress. 
The Tropical World : a popular Scientific Account of the Natural History 
of the Animal and Vegetable Kingdoms in the Equatorial Regions. By 
Dr. G. Haktwig, Author of “ The Sea and its Living Wonders.” 
London : Longman & Co., 1863. 
T HERE are, perhaps, few things which exercise so fascinating an 
influence upon the imagination of the student of natural history as 
the glowing descriptions given by travellers, of the aspects of nature in the 
tropical regions of the globe. Familiar as we all are with the moderate 
vegetation, with the sober tints of the birds and insects, and with the gene- 
rally unimposing and harmless character of the quadrupeds and reptiles of 
our own temperate climes, the contemplation of the marvels of form, of 
size, of strength, and of colour, exhibited by the productions of the tropics, 
inspire us at once with admiration and with awe. Beautiful as are our 
leafy groves of oak and beech, resonant with the melodious voices of brown- 
coated birds, and tenanted by the stately forms of oxen or deer, they lack 
at once the grandeur and the grotesqueness of the strange and giant vege- 
tation of the tropical forest ; they lack the wondrous birds which, like 
living gems, dazzle the sight, as they flash through the sunshine, or settle 
in the shade ; they lack the strange and unearthly sounds of the cam- 
panero, the howler, and the whip-poor-will, which seem to enhance the 
mystery of its gloomy recesses. Guided by the vivid descriptions of the 
veterans Humboldt and Waterton, we can picture to ourselves the pathless 
and interminable forests of Guiana, where Nature exuberates in perfect 
freedom from human interference— .now revelling in dense and impene- 
