TRANSMISSION OF MODIFICATIONS 373 



was also established, which was bound in time to produce better 

 specimens than ever before. 



3. That there has been direct transmission of the increased 

 vigor and powers of nutrition and growth that come from full 

 feed. 



The first conclusion is unthinkable. Nature must certainly 

 have produced, occasionally at least, perfect specimens of their 

 kind, and the belief that this is so is favored by the fact that 

 wild things do not respond generously to full feed. 



The second is without doubt a real fact in evolution, difficult 

 as it is to comprehend. Later, in statistical studies, it will be 

 found to our satisfaction that as the average is raised by selec- 

 tion new values appear at the top, a fact on which depends, 

 without doubt, a large share of our improvement of all species. 



And yet we cannot fight off the conviction that here, at this 

 point, lying so close to the very springs of life, the absolute con- 

 dition of life nutrition exerts a controlling influence upon 

 that mysterious force which we call the vital principle, and whose 

 relative strength we measure by such terms as "constitution" 

 and "vigor." That vigor, or the lack of it, is a transmissible 

 character no one will deny, or even doubt ; and it is the firm 

 conviction of the writer that when this vigor, or scale of living, 

 has been strengthened or weakened from any cause, the power 

 of the individual to transmit a vigorous constitution to its off- 

 spring will be enhanced or lessened accordingly, and that when 

 the last word shall have been spoken upon the disputed ques- 

 tion of inheritance or non-inheritance of acquired characters it 

 will be found to square with this fact. 



The writer desires, above all things, not to dogmatize. Facts, 

 not opinions, are needed in these uncertain fields ; and yet, until 

 the partisan advocates of the opposite sides of this question will 

 divide the question and discuss separately the three or four dis- 

 tinctly different issues involved, until that time, practical 

 breeders must not be deceived or lulled into carelessness by the 

 dictum that " acquired characters are not transmitted." 



Increased development above the natural in one form or 

 another is the principal object in all improvement, and a large 

 share of the possibility of such increased development lies in 



