REVIEWS. 
43 
more remarkable instance ; from its sap the “ Miel de Palma” (Palm-honey) 
is procured, and the trunk has been known to give 90 gallons of sap, even 
though cut down and thus detached from the soil. 
Our readers may endeavour to estimate the value of a classified collec¬ 
tion comprehending the varied products of the Palms alone; if embracing 
the whole range of the vegetable kingdom, it would not be easy to realize 
the proportionate importance of such a museum. London already possesses 
its museum of economic botany, instituted through the praiseworthy exer¬ 
tions of Sir W. J. Hooker, the respected director of the Koyal Garden. 
There ought to be a similar collection in the capitals, at least, of Ireland 
and Scotland. The best substitutes in the absence of such are works like 
that of Mr. Seeman’s. The diffusion of accurate information respecting 
the natural resources of different countries has made rather slow progress, 
and every contribution tending to promote the full development of such 
resources must be welcomed by every practical mind. 
In treating of each genus a distinct paragraph for botanical characters, 
geographical distribution, and useful products, is the method we should 
prefer. This has not been so systematically adhered to as it might. A 
synoptical table of genera, with at least the names of species comprehended 
n each, would also have added to the value of the 11 Popular History of 
Palms.” Nevertheless, we cordially recommend it as a valuable addition 
to the history of the sources of economic products. The book is illustrated 
by twenty coloured plates, representing twenty-five distinct species. These 
greatly add to its value. 
On the Variation of Species, with especial reference to the Insecta, 
followed by an inquiry into the Nature of Genera. By T. Vernon 
Wollaston, M. A., RL. S. 8vo. Van Voorst, London, 1856. 
The primary purpose of this little volume is to give in one view the results 
of Mr. Wollaston’s researches in the Madeira Islands, as they bear upon 
the causes and mode of variation in insects. He has drawn the illustrations, 
however, from a much wider field, and has made it a main object to call 
attention to the laws of geographical distribution in the same class of 
beings. Ascending, in the course of this inquiry, from the individual and 
casual variations to those which, attaining to a certain frequency and some 
degree of permanence, are qualified as varieties, the discussion has em¬ 
braced the ideas of species and genus, and their existence in nature. In 
respect to the former, there seems to be admitted, as a necessary postulate, 
