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NOTICES OF NEW BOOKS. 

The Senses of Insects. By Avucustr& Foren. Translated by 
MactErop YEARSLEY, F.R.C.S. Methuen & Co. 
Tis is a far more important publication than its title im- 
plies. It can in no sense be accepted as a purely entomological 
treatise, for it raises the primary question in animal psychology. 
Are instinct and reason distinct entities, or are they simply 
terms of a mental equation? Hither the genus Homo has no 
connection with the evolution of other animals, and possesses a 
mental capacity underived and specially created, or otherwice 
his reason, though far beyond, is not inseparable from the 
instinct of other animals. This is a problem that can perhaps 
be neglected by the ordinary zoologist, but it cannot be avoided 
by the psychologist. Hither all other animals than man are 
simply automata, or human intelligence is a derivative. As 
Dr. Forel remarks: ‘‘ Language and books are crammed with 
words which are taken for things,”’ and ‘‘reason”’ and “‘instinct”’ 
are words used to denote a fundamental difference while they 
only express items of a close relationship. This is not a con- 
clusion of the materialist, but will be a postulate of the theologian 
in the near future. 
Dr. Forel’s book, however, is not a disputation but a store of 
observations, his study of the senses of insects is profound, and 
he adds many new facts of his own discovery. He also advises 
caution in the method by which we attempt to gauge the sensory 
impressions of other animals: ‘‘ We have the bad habit of 
calling odoriferous substances (Retchstoffe) the substances which 
are cdoriferous for us. But the study of all animals very quickly 
shows us that the differences between the animal species are 
enormous, that a substance may be extremely odorous for one 
species and not so for another, and vice versé. The dog, whose 
sense of smell is of extreme delicacy for certain tracts that we 
are incapable of perceiving, is insensible to the scents which 
4ool. 4th ser. voi. XII.. July, 1908. Y 
