LLiit±.ki iil ii 



length the theories of heredity, i '< moment 

 it is enough to reflect that as liic utispring in 

 each suocessire generation spring from the 

 parent, the genn plasm may be thought of as 

 a continuous stream uniting the remotest ances- 

 tor of any given strain with the most recent 

 descendant 



Every tree in the orchard, for example, car- 

 ries within its tissues a portion of protoplasmic 

 chemical matter that has come down to it through 

 an almost infinite series of growths and divi- 

 sions in unbroken succession from the first tree 

 that ever developed on the earth-— or, for 

 that matter, from a vast series of more primitive 

 organisms that were the progenitors of the 

 first tree. 



And while this stream of primordial proto- 

 plasm has been changed by an infinitesimal 

 quantity in each successive era, it has retained 

 even to the present the fundamental character- 

 istics that it had from the outset. 



That such is the case seems little less than a 

 miracle; that an almost microscopical speck of 

 protoplasm which we term a pollen grain should 

 contain the potentialities of thousands of genera- 

 tions of ancestors, and should be able to transmit 

 them with such force that the seed growing from 

 the ovule fertilized by that pollen grain will 



