ACQUIRED CHARACTERS IN ANIMAL BREEDING 483 
gists, but in a more refined form. Semon, for example, has proposed the 
““Mnemetheorie” as founded upon two premises. First, that although 
the stimulations of the “sensitive substance of the organism” disappear 
as such, yet after they cease they leave behind in this same sensitive: 
substance changes which he has called Engramme. Second, that these 
‘‘Hngramme in the sensitive substance” persist not only in the soma, but 
also under favorable circumstances in the germ cells. This form of the 
“memory theory’ of heredity might seem to be a convenient hypothesis for 
explaining the assumed inheritance of modifications resulting from the use 
of organs, but it is difficult to imagine how it would favor the assumption 
of inheritance of modifications resulting from disuse of organs or loss of 
parts through mutilation. Obviously the inheritance of mutilations, in 
spite of a few circumstantial cases, cannot be maintained with any 
degree of conviction. ‘The many generations through which circumcision 
has been practised in the Jew and the deforming of women’s feet by the 
Chinese are two instances opposed to it. Dehorning of cattle, docking 
the tails of horses and sheep, clipping the ears of dogs, are instances 
which come within agricultural practice and have no permanent effect 
upon the breed. On the whole the neo-Lamarckians have come to 
believe, therefore, in the inheritance of those acquired characters which 
depend upon use or disuse of organs, achieved characters as distinguished 
from thrust characters. A rather crude example of this belief which has 
of late years obtained some notoriety among livestock breeders is Red- 
field’s theory of dynamic evolution. According to this statement of the 
belief, the exercise of any organ or function results in a corresponding 
storage of energy in the germ cells, such that the effects are transmitted 
to the next generation. The idea receives practical application from the 
further consequence, that this storage of energy having been granted, 
developed animals must of necessity possess more of it than those un- 
developed, and consequently such animals produce superior offspring. 
E. Davenport, Marshall, Pearl and others have taken issue with Redfield 
upon this subject and have demonstrated clearly that the facts which 
have been cited in support of his theory of dynamic evolution may be 
interpreted with far greater probability in other ways. In fact, the 
biological basis for such assumption as the storage of energy in germ cells 
is very slight. Moreover, the theory is evidently based upon a naive 
disregard of known biological facts, and a non-critical interpretation of 
statistical data. The matter deserves mention here, not because of any 
merit in it, but solely because of the publicity which has been accorded 
it in various journals devoted to practical breeding interests. 
As an example of the kind of agricultural data which those who 
believe in the inheritance of acquired characters point to for support 
of their views, nothing is more striking than the rise and improvement of 
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