LUTHER BURBANK 



of not as the tangible conveyer of any particular 

 "unit character", but as a receptacle in which 

 several or many factors or determiners of diverse 

 unit characters size of flower and color quality 

 of leaf and fruit and all the rest are assembled. 

 FURTHER AID FROM THE PHYSICIST 



But unfortunately the powers of the microscope 

 do not suffice to reveal these unit structures within 

 the chromosome. 



What they are like, must for the present remain 

 only a matter of conjecture. 



But that they are definite mechanical structures 

 of unthinkable smallness, represented by chemical 

 atoms in specific combinations, we can not doubt. 

 And in revealing to us the size and character of 

 these atoms, the modern physicist gives us aid in 

 supplementing the vision of the microscopist and 

 in helping to make it seem at least a possibility 

 that the definite factors of heredity have a physical 

 basis within the microscopic chromosomes. 



The conclusions that give this assurance are 

 based on various almost infinitely delicate tests 

 that are made in the modern physical laboratory. 



Summarizing these in a few words, it appears 

 that the physicist and chemist are now able to 

 make definite computations as to the size of the 

 molecules and atoms that make up the structure 

 of all matter. And the figures they present, when 



[234] 



