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vertebrate groups, has been very little studied at all by 
observers in this country. Most earnestly do we commend 
this study to those of our readers who wish to make their 
microscopes useful in the cause of science. Franz Leydig, of 
Tubingen, has devoted more attention than any other observer 
to comparative histology ; and his valuable £ Lehrbuch,’ 
filled with excellent woodcuts, is the best guide a student can 
have in this subject . 1 Insects, molluscs, worms, all furnish 
subjects of study most important in their bearing on the 
histology of man and the vertebrata. 
The histology of minerals may appear to some persons a 
curious association of terms. But, assuredly, the complex 
substance of a mineral may be spoken of as a “ web 
and the far-known researches of Sorby on the glass-cavities 
of crystals, and other matters relating to their origin and 
structure, lay the foundations of a mineral histology. 
The Embryology of plants and animals form a distinct and 
perhaps the most important branch of microscopical science 
in relation to all other knowledge, for without the microscope 
our knowledge of embryology would be nil, and without 
embryology we may fairly doubt if ever that grand doctrine 
of evolution which Herbert Spencer has taught would have 
been developed and laid its hold on men’s minds. In this 
country there is great want of a knowledge of embryology 
in general. In no manual or book of any kind in the 
English tongue is the development of invertebrates and of 
vertebrates treated in detail ; so that the student who ■would 
desire to aid in the solution of the many problems of the 
early development of Arthropods or Molluscs finds it difficult 
to gain a starting-point. The memoirs of Dr. Edouard » 
Van Beneden and of Dr. Emile Bessels — the former of 
whom studies the formation of the blastoderm, the latter 
its subsequent changes — will be found of great value. Dr. 
Van Beneden has studied the early changes of the ovum in 
all classes of animals, and is now about to publish his re- 
sults. The memoirs of Mecznikow on the development of 
Hemiptera and other insects are of the greatest value, but 
are not so accessible to English readers as French publica- 
tions. A volume on “ Development,” from the pen of Dr. 
Michael Foster, of University College, has long been looked 
for, and may be expected to contain a well-considered account 
of the embryology of all animals as far as the latest researches 
have gone. 
By Microzooloyy , Microphytology , and Micromineralogy 
in our list above we mean the study of minute organisms or 
1 A French translation of the work is published by Bailliere. 
