8 GENETICS 



source. In other words, an "hereditary character" of 

 any kind is not an entity or unit which is handed 

 down from generation to generation, but is rather a 

 method of reaction of the organism to the constellation 

 of external environmental factors under which the 

 organism lives. 



To unravel the golden threads of inheritance which 

 have bound us all together in the past, as well as to 

 learn how to weave upon the loom of the future, not 

 only those old patterns in plants and animals and men 

 which have already proven worth while, but also to 

 create new organic designs of an excellence hitherto 

 impossible or undreamed of, is the inspiring task before 

 the geneticist to-day. 



4. THE MAINTENANCE OF LIFE 



So far as we know, every living thing on the earth 

 to-day has arisen from some preceding form of life. 



How the first spark of life began will probably 

 always be a matter of pure speculation. Whether 

 the beginnings of what is called life came through 

 space from other worlds on meteoric wings, as Lord 

 Kelvin has suggested; whether it was spontaneously 

 generated on the spot out of lifeless components; 

 or whether life itself was the original condition of 

 matter, and the one thing that must be explained is 

 not the origin of life but of the non-living, no one 

 can say. Leaving aside the first speculation as un- 

 tenable and the third as irrational, since it jars so 

 sadly with what astronomers tell us of the probable 



