No. 385.] REVIEWS OF RECENT LITERATURE. 61 
whole animal kingdom as parts of one genetic scheme, in which the 
activities and traits of the beasts find their significance not through 
any fanciful analogy, but because they are the actual prototypes of 
the mental processes of the human mind itself. “If we regard man 
as the outcome of development through lower forms, according to vari- 
ation with natural selection — in a word, if man is the final link ina 
long chain binding the whole animal creation together, we have the 
greater reason for inferring that comparative psychology and human 
psychology have common roots. We must, in fact, believe in a 
mental or psychical evolution as well as in a physical (morphological) 
one” (p. 20). 
Into the detailed results of Professor Mills’s work we cannot enter 
here, but the problems with which comparative psychology has mainly 
to grapple can be stated in a few lines. 
1, Imagination in animals, the power to frame mental pictures of 
absent objects. 
2. The fact and extent of the power to count and deal with meas- 
urable quantities in general. 
3. The capacity to generalize upon details and to form abstract 
ideas. 
4. The sense of right and wrong, and the nature of moral sanction 
among the brutes. 
5. Their comprehension of man’s various forms of expression and 
the extent of their power of communication between each other. 
6. The homing and migrating instincts of animals and their reap- 
pearance in man. 
7. The laws of heredity and susceptibility of animals to modifica- 
tion through environment. ; 
Towards the solution of these problems Mr. Mills professes to 
contribute only material ; he is sparing in his deductions and faith- 
ful to the fact. “Plainly,” he says, “it will be desirable to keep our 
facts very sharply apart from our explanations. The science of psy- 
chology is a very youthful one ; that of comparative psychology still 
more so; and at the present stage of the science any one who con- 
«tributes a single fact will be a real friend to its progress.” The 
book is chiefly contributory of material, it is true, and such work Er 
long in process, and its conclusions concerning individual functions 
and species of animals are fragmentary and tentative ; but such delv- 
ing must necessarily precede and underlie all constructive theory. 
Mr. Mills’s work shows in a marked degree a qualification upon 
which must be founded all really successful study of animal life; 
