i6o HEREDITY 



pynamio striking examples of such reactions. When the bow 



impulses 



bear the of a vioHn is drawn across the strings force passes 



cliflrfl.ctpT 



of the parts along them and away, carrying with it and com- 

 they pro- municating to the air, and through the latter to the 

 human ear and brain, the peculiar characteristics 

 resulting from a certain length, thickness, and degree 

 of tension. The string has acted as a mould for the 

 force. It has imbued it with its properties. If we 

 wish to penetrate still deeper into the problem we 

 may say that it is the force inherent in matter which 

 has reacted on the force passing through it. So it is 

 with the essential parts of all musical instruments, 

 and so also with the tissues of the body. All forms of 

 force are alike in this respect : they are all influenced 

 by the matter from which they proceed. 

 The bed- When One reflects that the character of all 

 dynamic substancos, whatsoever be their origin, is determined 

 ^^' by the degrees of force by which their atoms and 

 molecules are held together, when one considers that 

 change of shape in any given mass can result only 

 through the addition or subtraction of force, the real 

 meaning and importance of this factor in physiological 

 processes will become apparent. In order that the 

 various parts of any organism should be reproduced 

 it is absolutely essential that they should be repre- 

 sented in some way in the spermatozoa or ova, as the 

 case may be. If there be no link between them no 

 reproduction can take place. Does this imply that 

 each kind of tissue is represented by a cell, or a part 

 of a cell, or a certain number of molecules in the 



