Views on the Nature of Organie Structure. 53 
dinum quibus Algarum regnum constituilur, by J. G. Agardh. 
The first part of the second volume appeared in July last. It is 
published at Lund, (Sweden,) and at Leipsic. 
We should not forget here to state that the accomplished algol- 
ogist, Professor Harvey, has completed the third volume of his 
admirable Phycologia Britannica, which finishes the work. The 
360 plates represent 378 species. A full synopsis of the orders, 
genera and species is appended, and new title-pages aud indexes 
are given, arranged for binding the work either in three volumes, 
according to the order of publication, or in four, systematically, 
according to the synopsis of the species. The cultivators and 
amateurs of our science may be interested to know that Professor 
arvey is now engaged upon his extensive memoir on the North 
American Algz, to be published under the auspices of the Smith- 
sonian Institution; and the plates of which promise to rival or 
excel those of the Phycologia Britannica, or of his Nereis Aus- 
tralis, which are so justly admired. The first part, containing 
the olive series of sea-weeds, is now in press. ‘The new edition 
of his Manual of British Alga, or rather a new work, the Man- 
ual of the British Marine Alg@, was issued by Van Voorst at 
the close of 1849, during the author's visit to this country. The 
sage illustrated by twenty-six plates, after the manner of 
t, Greville’s well-known Alg@ Britannica. 
Scheerer’s Enumeratio Critica Lichenum Europeorum et 
nova Methodo, §c., (Berne, 1830, 8vo, with 10 plates), is the 
latest and most important general work upon this order. 
Arr. VIII._— Views on the Nature of Organic Structure ; by 
Lieut. E. B. Hunr, Corps of Engineers, U. 8. A.* 
Turovenovur the whole range of organic existence, both ani- 
mal and vegetable, there is an evident adaptation of species and 
Magine its vital possibility except in its present astronomical 
wnat. Any great change from the earth’s valnes for gravita- 
hon, the atmospheric pressure, the average heat and light, or 
Steatly increased variations in these elements of condition, would 
as fatal to all our present species. Nor could these species 
ong survive a fundamental change in the atmosphere, the wa- 
tes, the vapors, or the soils of the present terrestrial system. 
