32 The American Naturalist. [January, 
illustrated with new figures that largely increase its value. It is the 
best single volume on the general subject that has appeared since — 
Darwin’s time, and it is doubtless destined to be for years to come the — 
The principle of continuity makes antecedently probable the theory 
of organic evolution. The probability is strengthened by the fact that ; 
a natural classification of organie beings seems with the advance of 
knowledge more and more evident. The evidence from Morphology — 
in the present volume is confined largely to a discussion of rudimen- — 
tary structures, and especially such as are found in the human body. — 
Muscles of the external ear, panniculus carnosus, feet, hands, tail, ver- 
miform appendix of the cxcum, ear, hair, teeth, perforation of the i 
humerus and flattening of the tibia are all treated. In this connection — | 
Dr. Louis Robinson’s recent interesting observations on the grasping — : 
power of the infant’s hand are reported. In discussing Embryology, — 
considerable space is devoted to the phenomena of fertilization and 
karyokinesis, since the author believes the great similarity in these 
highly complex and specialized processes, shown throughout the animal — 
and vegetable kingdoms, to be indicative of organic continuity, and 
hence evidence of the highest importance. The testimony afforded by i 
connecting links, which has accumulated mainly since Darwin first 
published, forms an interesting section, made more interesting by good i. 
figures. Geographical Distribution is mainly a summary of Wallaces 
observations. E 
' The evidence for and against the theory of Natural Selection is fully 
and fairly given. Romanes believes this principle to be not the sole, 
but the most important, factor of organic evolution. The main gen- — 
eral arguments in favor of the theory are three, viz., its inherent 
necessity, the facts of heredity, variation, and struggle for existence 
being excepted ; the fact that among all the millions of structures and 
instincts, each is developed for the benefit of its own species, and m 
not a single case for the exclusive benefit of another species; also the 
facts of domestication. Protective coloring, warning coloring and 
Ne o aE Sepp sagas E es OS Cg EE E SE E E re Ea nm E AS ATER 
similar organs in widely different groups (Mivart’s instance of the p 
of the cuttlefish and of vertebrates), and the preservation of the ft 
beginnings of structures (the Duke of Argyll’s “Prophetic Germs "h | 
