XXXVIIL] CONCLUSION. 341 



not, as far as inheritance is concerned, how injurious a 

 quality or structure may be if compatible with. life. No 

 one can read the many treatises on hereditary disease 

 and doubt this. ... A long catalogue could be given of 

 all sorts of inherited malformations, and of predisposition 

 to various diseases." Under "Cataract of the Eye" Mr. 

 Darwin writes at p. 9 : " When cataract affects several 

 members of a "family in the same generation, it is often 

 seen to commence at about the same age in each e.g., in 

 one family several infants or young persons may suffer 

 from it, in another several persons of middle age." This 

 latter observation has a direct bearing on the hereditary 

 diseases of plants which notoriously appear at certain 

 stages of the plant's growth. Under " The Horse " Mr. 

 Darwin quotes Youatt on p. 9, who writes : " There is 

 scarcely a malady to which the horse is subject which is 

 not hereditary." At p. 11 : "Andrew Knight, from his 

 own experience, asserts that disease is hereditary in 

 plants, and this assertion is confirmed by Lindley." And 

 again : " Seeing how hereditary evil qualities are, it is 

 fortunate that good health, vigour, and longevity are 

 equally inherited. ... As to the inheritance of vigour 

 and endurance the English racehorse offers an excellent 

 instance. Eclipse begot 334 and King Herod 497 

 winners." 



Facts like the above should serve as key-notes, and 

 strongly impress all practical agriculturists. Every 

 diseased plant or seed should be mercilessly struck out 

 and destroyed. No owner of herds and flocks would 

 allow badly diseased animals to breed, and, in the same 

 way, no agriculturist should take his seed from plants 

 notoriously infected. By a constant selection of seeds 

 from plants the freest from disease at length races 

 might be obtained almost entirely free from disease. If 

 it should some day be proved that disease does not exist 

 in seeds, it will not be denied that certain plants inherit 

 a strong tendency to become diseased. 



