216 TRANSMISSION OF ACQUIRED CHARACTERS 



(c) and (d) acted directly on the germ cells of the original subjects 

 of experiment ; and (3) there was some measure of artificiality in 

 the conditions under which the second generation developed which 

 may have disturbed the normal routine of reproduction. 



Breeders' Evidence. — The evidence given by breeders in sup- 

 port of the theory of modification-inheritance, which is a tacit 

 or an avowed belief of many, if not of most, appears to us in most 

 cases too full of vagueness and misunderstanding to be of signifi- 

 cance ; but it has been often adduced by expert biologists, notably 

 by Cope (1896), who cites his cases from Brewer (1892-3), an 

 acknowledged agricultural authority. The first argument relates 

 to the inheritance of characters due to nutrition, and is as follows : 

 The size of domestic animals is often of much practical import- 

 ance, and has been attended to for many years with all the 

 carefulness which a pecuniary stake ensures. It used to be said 

 that " feed is more than breed," but it is now recognised that 

 "heredity or 'breed' is the more important." There is also, of 

 course, careful selection, " but no breeder claims that a breed is 

 or can be kept up to extra size by selection alone." " Breeders 

 do not believe that the characters acquired through the feeding 

 of a single ancestor, or generation of ancestors, can oppose more 

 than a slight resistance to that force of heredity which has been 

 accumulated through many preceding generations, and is con- 

 centrated from many lines of ancestry. Yet the belief is universal 

 that the acquired characters due to food during the growing 

 period have some force, and that this force is cumulative in suc- 

 cessive generations. All the observed facts in the experience 

 with herds and flocks point in this direction." The breeding of 

 small and delicate Alderney cows was furthered by systematic 

 underfeeding of the calves. Large-sized breeds have originated 

 m regions of abundant food, and smaller breeds in districts of 

 scantier forage. " This can hardly be due to accident." In 

 short, " if these acquired characters are in no degree whatever 

 transmitted, then certain practices of breeders, which are 



