314 THE INDUCTIONS OF BIOLOGY. 



by remoter ancestors. The other is the limitation of Heredity 

 by sex — the restriction of transmitted peculiarities to off- 

 spring of the same sex as the parent possessing them. 



Atavism, which is the name given to the recurrence of 

 ancestral traits, is proved by many and varied facts. In the 

 picture-galleries of old families, and on the monumental 

 brasses in the adjacent churches, are often seen types of fea- 

 ture which are still, from time to time, repeated in members of 

 these families. It is a matter of common remark that some 

 constitutional diseases, such as gout and insanity, after miss- 

 ing a generation, will show themselves in the next. Dr. 

 Struthers, in his above-quoted paper " On Variation in the 

 Number of Fingers and Toes, and in the Phalanges in Man,'' 

 gives cases of malformations common to grandparent and 

 grandchild, but of which the parent had no trace. M. Girou 

 (as quoted by Mr. Sedgwick) says — " One is often surprised to 

 see lambs black, or spotted with black, born of ewes and rams 

 with white wool, but if one takes the trouble to go back to the 

 origin of this phenomena, it is found in the ancestors." 

 Instances still more remarkable, in which the remoteness of 

 the ancestors copied is very great, are given by Mr. Darwin. 

 He points out that in crosses between varieties of the pigeon, 

 there will sometimes re-appear the plumage of the original 

 rock-pigeon, from which these varieties descended; and he 

 thinks the faint zebra-like markings occasionally traceable in 

 horses have probably a like meaning. 



The other modified manifestation of heredity above referred 

 to is the limitation of heredity by sex. In Mr. Sedgwick's 

 essays, already named, will be found evidence implying that 

 there exists some such tendency to limitation, which does or 

 does not show itself distinctly according to the nature of the 

 organic modification to be conveyed. On joining to the evi- 

 dence he gives certain bodies of allied evidence we shall, I 

 think, find the inconsistences comprehensible. 



Beyond. the familiar facts that in ourselves, along with the 

 essential organs of sex there go minor structures and traits 



