Chai\ XIV. 



FIXEDNESS OF CHARACTER. 



63 



but without being able to assign any cause, that, when a new 

 character appears, it is occasionally from the first well fixed, 

 or fluctuates much, or wholly fails to be transmitted. So it is 

 with the aggregate of slight differences which characterise a new 

 variety, for some propagate their kind from the first much truer 

 than others. Even with plants multiplied by bulbs, layers, &c, 

 which may in one sense be said to form parts of the same individual, 

 it is well known that certain varieties retain and transmit through 

 successive bud-generations their newly-acquired characters more 

 truly than others. In none of these, nor in the following cases, 

 does there appear to be any relation between the force with 

 which a character is transmissible and the length of time during 

 which it has already been transmitted. Some varieties, such as 

 white and yellow hyacinths and white sweet-peas, transmit their 

 colours more faithfully than do the varieties which have retained 

 their natural colour. In the Irish family, mentioned in the 

 twelfth chapter, the peculiar tortoiseshell-like colouring of the 

 eyes was transmitted far more faithfully than any ordinary colour. 

 Ancon and Mauchamp sheep and niata cattle, which are all com- 

 paratively modern breeds, exhibit remarkably strong powers of 

 inheritance. Many similar cases could be adduced. 



As all domesticated animals and cultivated plants have varied 

 and yet are descended from aboriginally wild forms, which no 

 doubt had retained the same character from an immensely 

 remote epoch, we see that scarcely any degree of antiquity 

 ensures a character being transmitted perfectly true. In this 

 case, however, it may be said that changed conditions of life 

 induce certain modifications, and not that the power of inherit- 

 ance fails ; but in every case of failure, some cause, either 

 internal or external, must interfere. It will generally be found 

 that the parts in our domesticated productions which have 

 varied, or which still continue to vary-that is, which fail to 

 retain their primordial state,— are the same with the parts which 

 differ m the natural species of the same genus. As, on the theory 

 of descent with modification, the species of the same genus 

 have been modified since they branched off from a common 

 progenitor, it follows that the characters by which they differ 

 from each other have varied whilst other parts of the organi- 

 sation have remained unchanged; and it might be argued that 



