244 AGRICULTURE. 



II. Variation Furnishes the Starting-point 



1. Variation of Seeulings. 



2. Variation may be induced by — 



(i) Environmental Changes. 



{a) Change in Food-supply. 



{b) Light Relations. 



[c) Pruning. 

 (2) Cross-fertilization. 



[a) Limits of Crossing. 



{b) Varying Results of Crossin^^ 



{c) Process of Cross-pollinatior 

 3 Bud Variation. 



III. Fixing the Type. 



(7._REFERENCES. 



