64 THE AMERICAN NATURALIST. [VOL XXXIV. 
problems which have arisen in the neurology of higher forms shows 
that one cannot afford to neglect it. 
A second and perhaps less pardonable fault is the absolutely 
unqualified way in which the neurone theory is accepted and the 
light manner in which really serious objections to it are passed over. 
To read the author’s presentation of Apathy’s work one would think 
that this investigator’s results were almost in line with the neurone 
doctrine ; but an unbiased comparison shows this not-to be true. 
Surely the statements of Apathy, if correct, are more serious obstacles 
to the acceptance of the neurone theory than Barker is willing to 
admit ; and what is perhaps less consoling to an advocate of the 
theory is that these statements have received no small amount of 
confirmation at the hands of Bethe. 
The letterpress and numerous illustrations are excellent, and the 
volume is provided with two indices — one for subjects and the other 
for authors. In the subject index the two kinds of type used in the 
page numbers refer, we are told, in one case to text and in the other 
to figure reference; in the author's index two kinds of type are also 
employed, but, probably through an oversight, no explanation of their 
use is given. 
The defects which the book has are few compared with its excel- 
lencies, and we do not hesitate to pronounce it a masterly production 
of the highest quality of which Americans may justly be proud. 
GHP 
Neurone Theory. brochure on 
the neurone doctrine and its opponent has come from the pen of 
A. Hoche. The author gives a clear statement of the foundations 
of the theory, and then considers it in the critical light of recent dis- 
covery. His conclusions are that the neurone theory in its original 
form is no longer tenable, and that the fibrillar theory must replace 
it, so far as the histology of the adult nervous elements is concerned. 
The nervous elements develop as independent cells, and become 
secondarily connected by fibrillar growths, though in this later con- 
dition they reassert their physiological independence in the various 
aspects of their metabolism. The histogenesis and physiology of 
nervous elements, particularly their trophic relations, follow then on 
the lines laid down by the neurone theory, and in these respects this 
theory may still be said to be valid. Dg 
1 Hoche, A. Die Neuronenlehre und ihre Gegner. 51 pp. A. Hirschwald, 
Berlin, 1899. 
