RELATIONSHIP OF SPECIES. 93 



continue for generations, and as it is usually performed on 

 animals, entails housing in the same way and feeding on 

 (probably) a similar unvarying diet. 



This must result in time in a deprivation to the system of 

 anything tending to induce change or variety (with its probable 

 benefits) in the germ-plasm. 



This cannot be compared to the conditions which would 

 obtain on the various islands, &c, where inbred creatures such 

 as rabbits, &c, tend to multiply and increase. Here they get 

 access to varying foods, which in their individuality they no 

 doubt assimilate to varying degree, and where copulation with 

 cousins many times removed is at least possible : both these 

 causes ensuring some change in the system, however slight, 

 from the stagnation that must result from the close inbreeding 

 as practised by man, which cannot be compared to the natural 

 evoluting inbreeding which takes place in the case of the rabbits 

 quoted above, or such other examples as that of the red deer of 

 New Zealand or the buffaloes of Australia. The latter move 

 with the Unknown Cause of Evolution, the former against it, 

 or rather tries to do so. 



One may further reason that continued inbreeding may be 

 likened to the prolonged subdivision of the germ-cells of primi- 

 tive life, which goes on for a time, but ceases for some unknown 

 reason at a certain point, unless some other strange cell com- 

 bines with it to give it fresh vigour. Also, it seems likely that 

 the infertility of divergent forms can be more easily explained 

 by the growing dissimilarities of the germ-plasm. 



It only seems reasonable that the germ-cell should require, 

 as an inducement to give birth to a new life, a partner not too 

 extreme, neither too satiate, nor too uncongenial. If, as one 

 imagines, in the formation of cells, it is the union of the two 

 separate individuals that causes the renewed productive powers, 

 it would seem that inbred animals necessarily obstruct this 

 process; the mating cells would in these types supply no new 

 individuality to forward the above end. The rejection of a 

 dissimilar and uncongenial unit can equally well be imagined. 



Against the architectural theory : while mutations may and 

 apparently do occur in varying degree as regards outward form, 

 I am unable to find any definite or clear distinction between the 



