Existing Theories Unsatisfactory 
26. It must render intelligible the effects of 
castration on animals. 
Now, no existing theory of heredity can give 
anything approaching a satisfactory explanation 
of all these phenomena. 
It is for this reason that we refrain from criti- 
cally examining, or even naming, any of them. 
We are convinced that in the present state of 
our knowledge it is not possible to formulate 
anything more than a provisional hypothesis. 
It must not be thought that we consider the 
various theories that have been enunciated to be 
of no value. Erroneous hypotheses are often of 
the greatest utility to science, for they set men 
thinking and suggest experiments by means of 
which important additions to knowledge are 
made. 
We now propose to set forth certain facts of 
inheritance, and from these to make a few 
deductions—deductions which seem to be forced 
upon us. 
We would ask our readers to distinguish care- 
fully between the facts we set forth, and the 
conclusions we draw therefrom. The former, 
being facts, must be accepted. 
The interpretations we suggest should be 
rigidly examined, we would say regarded with 
suspicion, and all possible objections raised. It 
is only by so doing that any advance in know- 
ledge can be made. 
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