510 
REVIEWS. 
flowering of Dicotyledons and Monocotyledons does not appear to 
be explained. 
The lecturer goes on to say “ that of the Dicotyledonous trees, 
which belong to temperate regions, those which extend farthest to 
the north are either protected from cold by numerous layers of bark, 
as is the case with the Birch, or else are provided with juices not sus¬ 
ceptible of freezing, such as the essential oil, which occupies the so- 
called turpentine-vessels found in the bark and wood of the Coni- 
ferae.” This is very bad. The essential oil is a secretion, usually 
confined to distinct reservoirs, and not a juice or sap. The layers of 
birch bark may be thick enough ‘ to hold water’ for household, but 
certainly not, we think, for Dr. Daubeny’s theoretical purposes. 
An endeavour is made to show that “ herbaceous plants, whose 
roots sink very little below the surface, will be ill adapted in general 
for either extreme of climate, flourishing neither amongst the frosts 
of the polar regions, nor yet amidst the scorching heats of the tro¬ 
pics.” We very much need statistics upon the relative proportions 
of herbaceous and ligneous species in different Floras. The most 
woody Flora which has specially engaged our attention is, we think, 
that of Japan, where the climate is neither tropical nor arctic, and 
yet where we reckon ligneous species to form nearly 40 per cent, of 
the whole. It may be borne in mind that Palms, an eminently tropi¬ 
cal group, form no tap-root. 
With regard to the food afforded by species of Manihot in South 
America, Dr. Daubeny refers to but one species, though in his list 
of “ additions, &c.,” he speaks, on the authority of the Archbishop of 
Dublin, of another variety. Two species, Manihot Aipi and M. 
utilissima , the former sweet, the latter bitter Cassava, are described, 
with their respective varieties, and figured by Pohl, in his “ Plan- 
tarum Brasiliae leones, &c.” Tapioca, Dr. Daubeny states to be 
the same as Cassava; that it is the name under which the latter is 
imported into Europe. We have always understood differently; 
that the fine starch, from which the Tapioca is ultimately prepared, 
settles down from the water in which the Cassava is washed. 
Dr. Daubeny states that in Norway Wheat is cultivated as high as 
Drontheim, in lat. 59° ; in Sweden up to the 63° parallel. It would 
be remarkable were the western limit the lower, with the influence of 
the Grulf-stream so directly playing upon it. But Drontheim is in 
latitude about 63° 25' according to our best Norwegian map, and 
Sehubeler gives the northern limit of Wheat in the map accompanying 
his interesting “ Culturpflanzen Norwegens” at 64° 40'. The same 
botanist gives the northern limit of Eye in Norway at 69° 30', of Oats 
at 69°. 
Who are the Messrs. Favre and Gfoudin referred to at page 100, 
as in contradiction upon the transformation of Aegiiops into Wheat ? 
We presume Fabre and Gfodron. Dr. Daubeny does not venture, he 
says, “ to bring forward the case of the Aegiiops as affording any in¬ 
dependent support to the doctrine of Darwin regarding the gradual 
