342 THE AMERICAN NATURALIST. [VoL. XXXIII. 
duction the author points out the dependence of our higher mental 
_ activities on the materials furnished by our sense organs. Light, 
heat, sound, materials of taste and of smell, and direct external con- 
tact are the stimuli for the eye, ear, tongue, nose, and outer skin. 
These, the author declares, are all the forms of sensory stimuli and 
sense organs known. How such a statement is consistent with the 
author’s opinion as to the source of all our mental materials is diffi- 
cult to understand, unless he be a man to whom pain, fatigue, hunger, 
and thirst are unknown. 
The relation of sense organs to the medium in which the animal 
lives is next taken up. Organs of taste and touch are equally pos- 
sible to water- and air-inhabiting animals, but organs of smell, hear- 
ing, and sight are of necessity more restricted to the air-inhabiting 
forms. Smell, the author believes, is absolutely impossible to water 
animals, though he offers no explanation of the condition in fishes 
-where the organs which become olfactory in the air-inhabiting verte- 
brates are so well developed. 
The remainder of the lectures is devoted to a condensed account 
of the sense organs of the animal kingdoms. The so-called vegeta- 
tive senses—touch, smell, and taste—are first considered, and then 
what are dignified by the title of animal senses — hearing and sight 
—are dealt with. Practically nothing novel is introduced in this 
part of the work, the first portion reading like an abstract of 
Jourdan’s Senses and Sense Organs of the Lower Animals, and the 
second being in large part avowedly taken from Carriere’s little book 
on the eye. The popular treatment of a scientific subject is one of 
the most difficult tasks an author can set for himself, and to prescribe 
rules for such forms of composition is well-nigh impossible. Super- 
ficiality, however, is never to be tolerated, and superficiality is the 
characteristic of Dr. Steffan’s contribution. CH Pp. 
Eckstein’s Zoologie.!— The German medical student has to pass 
examinations in zoology and comparative anatomy, and as a result a 
number of these compendia exist, apparently intended to enable the 
student to cram for examination. We are familiar with several of 
these syllabi, and this of Eckstein seems, on the whole, the best. - It 
contains a large amount of information, clearly arranged under the 
heads of history, histology, comparative anatomy, physiology, embry- 
ology, Lantsceainge.t A geographical distribution, phylogeny, taxonomy, 
1 Eckstein, Professor Dr. Karl. Repetitorium der Zoologie, Ein Leitfaden fiir 
Studierende. Zweite Auflage. Leipzig, W. Engelmann, 1898. 8vo, viii + 435 pp- 
