384 



ELEMENTS OF GENEKAL SCIENCE 



While we should have difficulty in finding like objects of 

 the same kind, we should rarely fail to recognize the rela- 

 tionship of the same kind of objects. We can recognize oak 



trees, and many people can 

 distinguish between red 

 oaks, white oaks, black 

 oaks, etc. Even the de- 

 scendants of a given set 

 of parents bear such re- 

 semblances that we readily 

 recognize their relation- 

 ship. One family may 

 have common characteris- 

 tics that separate them from 

 other families of children, 

 but the different mem- 

 bers of the family have 

 distinctive characteristics. 

 396. The nature of vari- 

 ation. Individuals of the 

 same kind may differ from 

 one another in almost 

 every feature (fig. 177). 

 If one selects the most 

 widely different grains of 

 corn that he can find on a 

 single ear, he will usually 

 be surprised at the varia- 

 tion. This is still better 

 shown by selecting grains 

 from different ears grown in different places. These are 

 merely form and surface variations. Other kinds of varia- 

 tions in corn will be discussed later. 



Equally great variations are found in other seeds. For 

 instance, the seeds of the common ragweed usually have 



FIG. 177. Variation in wheat 



These heads are taken from wheat that was 

 grown by the Pima Indians. Note the wide 

 differences in characters of the heads. The 

 number of inferior heads is so great that 

 the yield would be small. Photograph by 

 R. M. Mead 



