404 TRANSMISSION 



and are for the most part subjected to the same surrounding 

 conditions. 



Carefully examined, this field, interesting as it is of itself, is 

 barren of evidence upon the transmission of habits, though it 

 is the one most often appealed to for proof of the inheritance 

 of acquired characters. The error lies in assuming a causative 

 relation between two acts which are similar. It is true that the 

 habits of the individual and the instincts of the race are similar. 

 They could not be otherwise, seeing that both depend upon the 

 presence of suitable organs, without which the particular act 

 would not be possible, and with which it is certain to appear 

 whenever suitable stimulus is encountered ; but habit is founded 

 upon instinct and not instinct upon habit. 



The conclusion which seems inevitable is this : that breeders 

 need have no fear that the habit of an individual, as such, vvill be 

 inherited by its offspring ; but the fact that the habit developed at 

 all is sufficient reason for knowing that its development is always 

 possible in the family line, whenever suitable conditions arise. 



The attention of the student is called to the fact that while 

 we have shown that instinct is not the result of habit, and there- 

 fore that its existence is no proof of the transmission of habitual 

 acts, yet this does not show whether or not the habitual use or 

 non-use of a part will affect the intensity of transmission of that 

 part, or the tendency to make use of it. Having put instinct 

 behind us where it properly belongs, we have now to inquire into 

 the effects of use and disuse. 



SECTION VII EVIDENCE FROM USE AND DISUSE 



The question is not whether use develops and disuse leads to 

 non-development or degeneracy. The facts on that point are 

 already well known. The inquiry is whether the effects of use 

 and disuse are transmitted ; whether their influence is direct, 

 not merely indirect by rendering the individuals less or more 

 able to meet the demands of selection ; whether specialization 

 of a part is in any way due to use, aside from its effect in 

 developing individuals separately and aside from its connection 

 with increased rigor of selection ; whether generalization and 



