854 WEIGHT AND GERMINATION OF CHAP. IX 



turnip, Brassica campestris ruta laga. Mr. Wilson 

 separated the largest and smallest seeds of this latter 

 plant, the ratio between the weights of the two lots 

 being as 100 to 59, and he found that the seedlings 

 " from the larger seeds took the lead and maintained 

 their superiority to the last, both in height and thick- 

 ness of stem."* Nor can this difference in the growth 

 of the seedling turnips be attributed to the heavier 

 seeds having been of crossed, and the lighter of self- 

 fertilised origin, for it is known that plants belonging 

 to this genus are habitually intercrossed by insects. 



With respect to the relative period of germination of 

 crossed and self-fertilised seeds, a record was kept in 

 only twenty-one cases ; and the results are very per- 

 plexing. Neglecting one case in which the two lots 

 germinated simultaneously, in ten cases or exactly one- 

 half many of the self-fertilised seeds germinated before 

 the crossed, and in the other half many of the crossed 

 before the self-fertilised. In four out of these twenty 

 cases, seeds derived from a cross with a fresh stock 

 were compared with self-fertilised seeds from one of the 

 later self-fertilised generations ; and here again in half 

 the cases the crossed seeds, and in, the other half the 

 self-fertilised seeds, germinated first. Yet the plants 

 of Mimulus raised from such self-fertilised seeds were 

 inferior in all respects to the crossed plants, and in 



* ' Gardeners' Chronicle/ 1867, by long-continued selection, may 

 p. 107. Loiseleur-Deslongchamp have given to the grains of the 

 (' Les Ce'reales,' 1842, pp. 208-219) cereals a greater amount of starch 

 was led by his observations to or other matter, than the seed- 

 the extraordinary conclusion that lings can utilise for their growth, 

 the smaller grains of cereals pro- There can be little doubt, as 

 duce as fine plants as the large. Humboldt long ago remarked, 

 This conclusion is, however, con- that the grains of cereals have 

 tradicted by Major Hallet's great been rendered attractive to birds 

 success in improving wheat by in a degree which is highly ra- 

 the selection of the finest grains. jurious to the species. 

 It is possible, however, that man, 



