1M;A( TIC Al, LAWS ol" lAVK 



:i:i' 



(i^-r^ 



liiqluT than till' worms and soim* iiisft-ts have cuiiil* to (h*- 

 peiid upon it entirely. In st-xnal iv[)ro(hiction each indi- 

 vidual is huilt n[) hy the niini»-linL; of the j^^crniinal rlcnimls 

 of two parents, and nol only that, hut of fom- L^randpareiils, 

 eiyht great nrand[)arL'nls, and so on. This niin'^lin*^, hv pre- 

 poteiiee of some characters and recession of others, causes 

 active variation, an<l this seems to In- the chief pur[)ose of 

 bisexual reproduction, liy statistical analysis (ialton proved 

 that an inihvidual receives on the average ">() per cent of Ins 

 characters from his ^^^^^ ^^ 



parents, 25 per cent (£^hHp 



from his grandpar- 

 ents, and tlie rest 

 from more remote an- 

 cestors. (ii\en all the 

 forces of increase, va- 

 riation, and heredity, 

 another law comes hito 

 play, the discovery of 

 which was Darwin's 

 great contribution. 



The law of natural selection. Xttfurr srirrfx fhc fittest tn 

 survive. From the becfinidno-, man has imitati'd nature in 

 selectino- the i)lants and animals that suit his need or fanev, 

 and this is connnonly distiiiLiuisluMl as ((r(.'fict\t/ .srhctiou. 

 Combination of tliese two ])rocesses has resulted in \]\o sp(»- 

 cies and varieties, strains and breeds, that we nnw .sec in the 

 world. Progress has been made in the [tast chielly by pick- 

 ing up chance variations as they have occurred in nature and 

 accidentally among domesticated j)lants and animals. ( )nly 

 within recent years haxc we begun to learn how to sidi'ct 

 the parents in order to cause desired vaiiations. \\\ eight 

 years of most accui-alc :nid ]iainstaking experiments in cn^ss- 

 ing and rearing \arietics of garden ju-as, the Austrian monk. 



(dd) @)~T~@) ^^ ^® 



abviuf. 



Vu,. 104. Diaiirani illustratiiiLr Mt'iidel's law 



of (lihybrids. white lu-iiii,^ (l(»iniiiiiiit and 



black recessive 



