916 - Scientific News. [December, 
the physical influences upon the organism. The first tends to 
preserve uniformity, the second modifies the action of the first. 
The law of natural selection asserts that some individuals are 
stronger and better fitted to compete with others in the struggle 
of life, than are others of the same species ; hence they will live 
and perpetuate their kind, while the others die out. An errone- 
ous impression exists that Darwinian doctrines are more or less 
supported by all naturalists who accept evolution, but it is far from 
the truth. The Darwinian hypothesis is so very easy of applica- 
tion, and saves so much trouble in the way of investigation, that 
it is very generally employed without the preliminary caution of 
a rigid analysis of the facts, and it is safe to say that it is often _ 
misapplied. A great amount of nonsense has been written about 
its being a fundamental law, in all forgetfulness that we are yet to 
find a law for the origin of the variations upon which it acts; it 
cannot be the primary cause of the variations, for the laws of 
heredity are still more fundamental. The speaker then described 
the situation and character of Steinheim, where numerous shells 
of the Planorbidz are found in the strata, which have been very 
series has its own set of characteristic differences, and its own 
peculiar history. It isa fair inference from the facts before us, 
that the species of the progressive series, which become larger 
and finer in every way, owe their increase in size to the favorable 
physical condition of the Steinheim basin. Darwinists would say 
that in the basin a battle had taken place, which only the favored 
ones survived. Mr. Hyatt endeavored to present, in a popular 
manner, the life-history of a single species, the Planorba levis, 
and its evolution into twenty or thirty distinguishable forms, 
most of which may properly be called by different names and 
considered as distinct species. He also endeavored to bring the 
conception that the variations which led to these different species 
were due to the action of the laws of heredity, modified by physi- 
forces, especially by the force of gravitation, into a tangible 
form. ere are many characteristics which are due solely to the 
action of the physical influences which surround them; they vary . 
with every change of locality, but remain quite constant and uni- 
form within each. 
— Dr. E. L. Trouessart communicates a valuable essay in de- 
fence of the doctrine of derivation to No. 16 (October) of the 
Revue Scientifique. He states the position of the objectors to 
