SEEDS AND SHOOTS 3 



or accident before the plantlet can escape. Other kinds have 

 a more or less definite period of dormancy, within which time 

 they will not germinate even though conditions are favorable. 

 Seeds of many of the wild herbaceous perennials will not 

 germinate till the following spring. Other seeds lie in the 

 ground two or three years before germination. On the other 

 hand, the seeds of some species germinate at once on maturity, 

 even while on the parent plant as in the case of the mangrove. 

 Special soils or other media, as to acidity, alkalinity or other 

 qualities, may be necessary for germination and growth, or 

 particular treatment, as etherization, may yield new results; 

 and] in some plants, as the orchids, it is now supposed that 

 certain fungi are necessary to germination. 



Thus far, the knowledge of conditions and aptitudes is chiefly 

 empirical, mostly the result of repeated and repeated trials, 

 with their failures and successes. We must always learn these 

 requisite conditions by experience; yet we are gradually dis- 

 covering a rational basis for our operations, and we may expect 

 marked progress in this direction in the years to come, render- 

 ing the propagation of plants more definite and predictable. 



THE PHYTON 



It is not alone by seeds that plants multiply themselves. 

 Many kinds rarely produce good seeds, and some of the culti- 

 vated species are multiplied practically exclusively by the non- 

 sexual and vegetative parts. Familiar examples are the sweet 

 potato, horse-radish, sugar-cane in the United States, banana. 

 Some species seem to be losing the power to produce seeds with 

 the enormous artificial development of other parts, as the Irish 

 potato. 



We may liken a plant to a colony of potential individuals, 

 one individual being perhaps a node and a leaf, one growing 

 on another and the aggregation making up a complex organism. 



