ORGANIC EVOLUTION RECONSIDERED. 1297 
ORGANIC EVOLUTION RECONSIDERED. 
The study of reproduction has prepared the student for the 
comprehension of certain views of the origin of the forms of 
life which could not be as profitably considered before. 
While the great majority of biologists are convinced that 
there has been a gradual evolution of more complex organisms 
from simpler ones, and while most believe that Darwin’s the- 
ory furnishes some of the elements of a solution of the problem 
as to how this has occurred, many still feel that the whole ex- 
planation was not furnished by that great naturalist. 
Accordingly, we shall notice very briefly a few of the more 
important contributions to this subject since Darwin’s views 
were published. 
In America, under the influence of the writings of Cope and 
Hyatt, a school of evolutionists has been formed, holding doc- 
trines that constitute a modification of those announced in 
cruder form by Lamarck, hence termed neo-Lamarckianism. 
These authors have imported consciousness into the list of 
factors of organic evolution and given it a prominent place. 
They regard consciousness as a fundamental property of proto- 
plasm; it determines effort and the direction that activity shall 
take: thus hunger leads to migration, and brings the creature 
under a new set of conditions which influence its nature. A 
certain proportion of the changes an animal undergoes are at- 
tributed to the direct influence of surrounding conditions (en- 
vironment), but the larger number are owing to efforts involv- 
ing the greater use of some parts than others, which tends to 
become habitual. This is the explanation neo-Lamarckianism 
offers for the origin of variations, It is assumed that the re- 
sults of use or disuse of parts is inherited, so that the gain or 
loss is not transient with the individual, but remains with the 
group. 
This theory also refers the loss or preservation of certain 
structures to “acceleration ” or “retardation” of growth; thus, 
if the growth of gills were greatly and progressively retarded 
during embryonic life, they might become only rudimentary, 
and this would furnish an explanation of the origin of rudiment- 
ary organs, though it is clear that use and effort could not di- 
rectly explain such acceleration or retardation. It is further a 
fact, which this theory does not explain, that all variations of 
structure produced by use are not inherited. 
