Chap. XXVIII. 



CONCLUDING EEMARKS. 



409 



*d* 



diminished. With plants we see wonderful differences in the 

 stones of various fruits.. In the Cucurbitacese several highly 

 important characters have varied, such as the sessile position of 

 the stigmas on the ovarium, the position of the carpels within 

 the ovarium, and its projection out of the receptacle. But it 

 would be useless to run through the many facts given in the 

 earlier chapters. 



It is notorious how greatly the mental disposition, tastes, 

 habits, consensual movements, loquacity or silence, and the tone 

 of voice have varied and been inherited with our domesticated 

 animals. The dog offers the most striking instance of changed 

 mental attributes, and these differences cannot be accounted for 

 by descent from distinct wild types. New mental characters 

 have certainly often been acquired, and natural ones lost, under 

 domestication. 



New characters may appear and disappear at any stage of 

 growth, and be inherited at a corresponding period. We see 

 this in the difference between the eggs of various breeds of the 

 fowl, and in the clown on chickens ; and still more plainly in 

 the differences between the caterpillars and cocoons of various 

 breeds of the silk-moth. These facts, simple as they appear, 

 throw light on the characters which distinguish the larval and 

 adult states of natural species, and on the whole great subject 

 of embryology. New characters are liable to become attached 

 exclusively to that sex in which they first appeared, or they 

 may be developed in a much higher degree in the one than 

 the other sex ; or again, after having become attached to one 

 sex, they may be partially transferred to the opposite sex. 

 These facts, and more especially the circumstance that new 

 characters seem to be particularly liable, from some unknown 

 cause, to become attached to the male sex, have an important 

 bearing on the acquirement by animals in a state of nature of 

 secondary sexual characters. 



It has sometimes been said that our domestic productions do 

 not differ in constitutional peculiarities, but this cannot be 

 maintained. In our improved cattle, pigs, &c, the period of 

 maturity, including that of the second dentition, has been 

 much hastened. The period of gestation varies much, but has 

 been modified in a fixed manner in only one or two cases. In 



