94 



THE BEGINNINGS OF LIFE. 



however long the developmental processes may be which 

 have to be passed through before the parent form can 

 be assumed. The human ovum develops as surely into 

 a human being, as that of a fish does into a similar fish. 

 The process is, in fact, everywhere the same— whether 

 we have to do with mammal, bird, reptile, or fish or 



AmKb 



Hyd) 



In 



/ 



each case there is a reproduction of like from like, quite 

 irrespective of the grade of development which has been 

 attained by the parent organism. These phenomena 



have been generalized under a 



Heredity 



meaning (after the most careful consideration 

 of the facts) has been thus admirably rendered by 



Mr. Herbert 



He 



<^ Bringing the ques- 

 tion to its ultimate and simplest form, we may say 

 that, as on the one hand physiological units will, 

 because of their special polarities^ build themselves into 

 an organism of a special structure; so, on the other 

 hand, if the structure of this organism is modified by 



modified function, it lulll impress some corresponding 



'difii 



on the structure and polarities 



units. 



on 



The units and the aggregate must act and re-act 

 each other. The forces exercised by each unit on the 

 aggregate and by the aggregate on each unit must 

 ever tend towards a balance, 

 the units will mould the aggregate into a form in 

 equilibrium with their pre-existing polarities. If,, con- 



If nothing prevents 



1 < 



Principles of Biology,' vol. i. p. 256. 



1 



\ 







brio 



.1 



gst simple orT 



m '' 



hich separates, 

 AV of develop'' 



so we find tl 



^iidm powers of 



c 



31 special 



emorpl 

 "fgansi. \ 



m 



"*'e functio 



n 



'* from the i 



\ and ia 





