REVIEWS—SCIENTIFIC MANUALS, ETC. 49 
tion. In the case of the Protozoa, this may be all that most people 
need or could ‘profit by, but as we rise in the animal kingdom, such 
a manual would appear very meagre. We see announced as forth- 
coming, another Zoological volume from the pen of the author of that 
which lies before us, and a Botanical one from that of Professor 
Harvey of Dublin. We are curious to see whether the present 
manual is to be a model as to size, and if so, how the learned authors 
will acquit themselves in such trammels; but our present business is 
with Professor Greene’s manual of the sub-kingdom, Protozoa. It 
must in the first place be conceded that in this department of 
zoology, accessible and trust-worthy information is greatly needed, 
and would be gladly received by a large class of readers. Professor 
Greene appears to be well acquainted with what has been written on 
the subject, and has laudably exerted himself, to give a clear, though 
much compressed account of what is known, in relation to these 
elementary forms of animal life. We are not satisfied with his mode 
of treating their classification. He regards them as being as yet too 
hittle understood for the limits of classes and orders to be well deter- 
mined, and therefore only gives under the titles of the several groups 
which have been proposed, the subdivisions recommended by the 
authors who have chiefly studied them, accompanied by such struc- 
tural and physiological particulars respecting at least some typical 
species as seem to be established by sufficient authority. For prac- 
tical usefulness we should have preferred some attempt, even if con- 
fessedly only provisional, to harmonise what we seem to have learned 
from various investigators into a consistent system whose parts are 
brought into proper relation to each other and to the whole; and we 
confess we have no such ideas as to the necessary foundations and 
limits of what are entitled to be called classes and orders, as would 
deter us from applying these terms to the greater and secondary 
divisions, which, though liable to modification by increasing know- 
ledge, seem now to express the relations of the creatures, which we 
agree with the author in regarding as a distinct, well established sub- 
kingdom of the animal kingdom. He indeed complains of the char- 
acters of Protozoa being almost wholly negative, but this may 
perhaps appear to be almost unavoidable in a lowest division of any 
large collection of objects. In the vegetable kingdom, the method 
we prefer, separates as a sub-kingdom, those plants which are without 
Vascular tissue—the mode of diposing that tissue when present, 
Vou. V. E 
