1884.] 
Analyses of Books. 
547 
we are travelling in that direction is a different question. We 
are certainly not authorised to speak on behalf of orthodox 
Dai winists ; but we doubt whether any of them would admit 
that all animal species are necessarily moving upwards. Some 
of them are retrograding ; some of them, even on the supposi- 
tion that the development of species takes place “ mainly through 
the transmission to posterity of accumulated chance variations,” 
may remain stationary. We do not know, with any approach to 
certainty or completeness, all the conditions under which varia- 
tion occurs. Further, ex hypothesis those variations only will be 
preserved which are beneficial to the animal. It may well be 
that the “ terminal forms ” enumerated by Dr. Cleland may be 
such in which the vital conditions are hostile to variation. It 
may indeed be — though the idea approaches the position of 
Prof. Cleland more nearly than that of Darwin — that the capacity 
of variation in any animal line is not infinite. 
We are very far, however, from supposing that these consider- 
ations are sufficient to dispose of the author’s contention. The 
subjedt is one requiring a much more profound examination than 
it can here receive. Dr. Cleland, indeed, deserves the gratitude 
of biologists for having raised this interesting question, 
Text-Book of Descriptive Mineralogy. By Hilary Bauermann, 
F.G.S. London: Longmans and Co. 
We have here a compadt and clear manual of the descriptive 
portion of mineralogy. The illustrations are excellent in their 
class, being a reprodudtion of those used in the work of Brooke 
and Miller. 
In the introdudfory chapter we find some remarks on mineralo- 
gical nomenclature, a department of the science which has not 
yet reached perfedtion. The names of minerals are not in all 
cases cosmopolitan. Thus, to take instances here quoted, the 
substance known in England and Germany as Leucite is called 
Amphigene by French and Italian mineralogists, whilst “ Ido- 
crase, used in France and England, is equivalent to the German 
Vesuvian.” 
The sources of names are extremely variable. We have some 
derived from the writings of Pliny and Theophrastus, others 
from the German metallurgists of the fifteenth and sixteenth cen- 
turies. Complimentary names, first originated by Werner, have 
multiplied exceedingly, and however objectionable in some 
respedts, have at least the advantage of brevity. Local names, 
the author justly remarks, may be either good or bad. Thus, 
when a very widely-distributed mineral is called from some one 
