[May, 
294 Analyses of Books, 
polariscope does most important work, and is used in a much 
more delicate manner than is usual with the generality of ob- 
servers. A new field of research is now open to the microscopist 
and geologist. The figures on the plate certainly show that 
textures hitherto considered homogeneous, owing to the negleCt 
of suitable means of observation, possess a vast amount of 
structural detail. These discoveries have resulted in the forma- 
tion of that branch of Mineralogy known as “ Petrology,” which 
bears the same relation to Geology as Histology to Biology in 
general. 
The Plates are interleaved with very full explanations, which 
can easily be utilised for the purpose of reading the book by its 
illustrations, and referring from them to the text, as may be 
required, a method suggested and carried out very perfectly by 
Dr. Beale, in his “ How to Work with the Microscope.” Plate 2 
will be found very useful, as it contains figures illustrating some 
of the more common forms of adulteration. 
The book can be strongly recommended to those students 
who wish to learn, as for those who wish only to pass manuals 
are legion. 
Darwin and Modern Evolution, An Address delivered to the 
Essex Field Club, January 27th, 1880. By Raphael 
Meldola, F.R.A.S., F.C.S., &c., Retiring President. 
Concerning the former, or what might be called the business 
portion of this interesting address, we need say little beyond ex- 
pressing our satisfaction at the progress of the Essex Field Club, 
and at the work it is evidently doing. This work is of a two- 
fold nature, it is concentrating and systematizing the labours of 
local geologists, botanists, entomologists, archaeologists, &c., 
many of whose observations might otherwise fail to be recorded ; 
and it provides an organization for defending the interests of 
Science, whenever needed. We have had very recently proof 
that the lovers of Nature, if once organized, form a power which 
the authorities, local and national, will have in future to take 
into account. We only hope that other similar bodies through- 
out the realm may exert themselves as successfully as the Essex 
Field Club has done, under the able and zealous guidance of its 
late President, and that all may co-operate whenever there is any 
good end to be secured, or any threatened evil to be warded off. 
Turning to the more general part of the address, it must be 
admitted that the life and work of Charles Darwin form no easy 
subject to handle. So much has he, especially during the last 
twelve months, occupied the attention of the intellectual world, 
