NUTRITION AND GENESIS. 477 



accompany the fall from a high to a moderate nutrition. The 

 confounding of these two relations has led to mistaken infer- 

 ences. When treating of Genesis inductively, we reached the 

 generalization that " the products of a fertilized germ go 

 on accumulating by simple growth, so long as the forces 

 whence growth results are greatly in excess of the antagonist 

 forces; but that when diminution of the one set of forces, oj 

 increase of the other, causes a considerable decline in this ex- 

 cess, and an approach towards equilibrium, fertilized germs 

 are again produced.'' (§ 78.) It was pointed out that this 

 holds of organisms which multiply by heterogenesis, as well 

 as those which multiply by homogenesis. And plants were 

 referred to as illustrating, both generally and locally, the 

 decline of agamic multiplication and commencement of gamic 

 multiplication, along with a lessening rate of nutrition. Now 

 the many cases which are given of fruitfulness caused in trees 

 by depletion, are really cases of this change from agamo- 

 genesis to gamogenesis; and simply go to prove that what 

 would naturally arise when decreased peripheral growth had 

 followed increased size, may be brought about artificially by 

 diminishing the supply of materials for growth. Cramping 

 its roots in a pot, or cutting them, or ringing its branches, 

 will make a tree bear very early: bringing about a prema- 

 ture establishment of that relative innutrition which would 

 have spontaneously arisen in course of time. Such facts 

 by no means show that in plants sexual genesis increases as 

 nutrition diminishes. When it has once set in, sexual 

 genesis is scanty or imperfect unless nutrition is good. 

 Though the starved plant may blossom, yet many of its 

 blossoms will fail; and such seeds as it produces will be ill- 

 furnished with those enveloping structures and that store of 

 albumen, &c, needed to give good chances of successful ger- 

 mination — the number of surviving offspring will be dimin- 

 ished. Were it otherwise, the manuring of fields which are to 

 bear seed-crops, would be not simply useless but injurious. 

 Were it otherwise, dunging the roots of a fruit-tree would in 



