Phenomena of Inheritance 73 



BLENDING ALTERNATIVE PARTICULATE 



O 



FIG. 23. DIAGRAM TO ILLUSTRATE THREE KINDS OF INHERITANCE described 

 by Galton. (After Walter.) 



cases were called by Galton "blending" inheritance (Fig. 23). 

 Sometimes characters appear in offspring which were "latent" 

 in the parents but were "patent" in one or more of the grand- 

 parents ; such skipping of a generation, during which a character 

 remains "latent," has long been known as "atavism." At other 

 times characters which were present in distant ancestors, but 

 which have since dropped out of sight or have remained "latent," 

 reappear in descendants ; such cases are known as "reversions." 



In still other cases certain characters appear only in the male' 

 sex, others only in the female, this being called "sex-limited" in- 

 heritance ; while in some instances characters are transmitted from 

 fathers through daughters to grandsons or from mothers to sons, 

 all such cases being known as "sex-linked" inheritance.* 



2. Nciv Characters or Mutations. But in addition to these 

 permutations in the distribution and combination of ancestral 

 characters new and unexpected characters sometimes develop 

 in the offspring, which were not present, so far as known, in any 

 of the ascendants, but which, after they have once appeared, are 

 passed on by heredity to descendants. Such inherited variations 



* See p. 180. 



