LECTURES AND ESSAYS. 425 



are carried perhaps hundreds of miles before they lodge on the banks. 

 Many seeds have appendages by which they are borne about by the wind. 

 The testa of cotton seeds is entirely covered witb long hairs, the cotton of 

 commerce, while others, as milkweed, have tufts of hairs large enough to 

 buoy them up. The keyed or winged seeds of maple, ash, elm and catalpa 

 are sometimes carried long distances both by wind and water. The thistle 

 and many other forms of the compositae, have a hairy pappus, an outgrowth 

 of the calyx, by which the seeds are scattered. Many fruits are eaten by 

 animals and the seeds are thus widely distributed. The beggar ticks 

 (Biclens) and beggars lice (Desmodhcm), with their barbed hooks and hairs, 

 are notorious deadbeats in securing free transportation, and attach them- 

 selves to the coverings of man and animals with a pertinacity worthy of a 

 better cause. The seeds of some of the Australian grasses, not content with 

 fastening themselves to the wool of sheep, use their awns for boring into 

 their bodies, and sometimes their internal organs become filled with them. 



Most seeds germinate in the ground, but some plants are parasites and 

 force their roots into the stems of other plants. Such seeds are covered 

 with a sticky substance, and when they fall on a branch this holds them 

 fast until they have taken root. 



Commerce is also, unwittingly, responsible for the dissemination of seeds, 

 as the hay and straw shipped from one part of the country to another, 

 either as fodder or as a packing for fragile articles, is often full of seeds, 

 many of them those of injurious weeds which spring up and occupy the 

 land. Grass and other fine seeds often have seeds of noxious weeds mixed 

 with them; and the importation has been carried so far that more than one- 

 half of our worst weeds are of foreign origin. 



Nature plants her seeds by covering them with leaves and grass, or assists 

 them to work their way into the soil by an alternate freezing and thawing 

 in the spring. 



The agricultural seedsman does not trust to Nature's planting, but care- 

 fully gathers them, and when seed time comes commits them to the care of 

 mother earth. Seeds are capable of germination long before they are fully 

 ripe. If immature seeds are planted the per cent of germination will 

 probably be low, although it will take place quicker than with ripe seed, and 

 as the food supply of the plantlet is limited it will be weak and feeble, but 

 if in rich soil, they may become strong plants ripening a full crop, earlier, 

 perhaps, than ripe seed. Experiments thus far conducted do not favor the 

 use of immature seed, although there may be a time, as the seeds are approach- 

 ing maturity, when they can be gathered, and will produce ripe fruits, 

 slightly earlier than if allowed to reach their full development. 



Experiments in which the seeds were selected from different parts of the 

 plants, or of the fruits, have been tried, but, everything else being equal, 

 without decided results. Experiments with seed corn comparing the yield 

 of the six rows of kernels at the tip, the six middle rows, and the six rows 

 at the butt of the ear, indicate that, from an equal number of plants, the 

 yield of the tip kernels equals, if it does not exceed, that of the middle and 

 butt kernels, but to balance this the latter have a slightly higher germinat- 

 ing power. 



The very best results have been obtained from the use of selected seed, 

 and not only have beneficial effects been secured by choosing the seed from 

 the most perfect fruits, but large and fine fruits are reproduced in their 



