REVIEWS OF RECENT LITERATURE. 
GENERAL BIOLOGY. 
A Rational Vitalism.— A most significant feature of the biological 
thought of to-day is the effort to place upon a solid foundation the 
idea of elementary vitalistic phenomena as thinkable processes, which 
are independent of all known chemical and physical forces and as 
worthy of scientific recognition and as capable of exact.statement as 
is gravitation or chemical affinity. 
Driesch in a recent paper’ seeks to furnish a proof of the exist- 
ence of vitalistic phenomena of an elementary character, not by 
bringing forward new facts, but by the interpretation of already pub- 
lished observations in the domain of experimental morphology. It 
should be at once mentioned that, whereas Driesch combats strongly 
the absolute dominance of the mechanical theory of life processes, 
as confusing that which is merely understandable with that which is 
actual and capable of proof, and so as becoming dogmatic and mis- 
leading, he clearly discountenances the older uncritical vitalism with 
its implied supernatural teleology and its absence of all well-defined 
relation to the fundamental ideas of causality, energy, matter, etc. 
The author looks to the problem of localization of morphogenetic 
processes as the divining rod by the aid of which we may be led into 
this new land of promise. Why is it that the archenteron of the well- 
developed gastrula of Sphzrechinus becomes constricted in two 
places, thus marking off from one another the stomadzum, mesen- 
teron, and proctodeum? Moreover, why do similar constrictions 
occur in the archenterons of each of the two half embryos, which 
result from the dividing in the equatorial plane of a well-developed 
gastrula in such wise that each half contains its share of the endo- 
derm as well as of ectoderm? The wound heals, and the constric- 
tions occur in each embryo at the same proportionate distances 
from the poles of the embryo as in the normal larva. The cause 
of this phenomenon, and of others similar to it, is hot to be found, 
1 Driesch, H. Die Localisation morphogenetischer Vorgänge: Ein Beweis vita- 
listischen Geschehens. Leipzig, 1899. 82 pp. Published also in Archiv für 
Entwicklungsmechanik, etc., Bd. viii, 1, pp. 35-111, 1899. 
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