3 2o TEE POPULAR SCIENCE MONTHLY 



in by accidental mixture. In either case they can presumably be got 

 rid of. I may even go further and express a doubt whether that degen- 

 eration which is vaguely, supposed to be attendant on all seed crops is a 

 physiological reality. Degeneration may perhaps affect plants like the 

 potato which are continually multiplied asexually, though the fact has 

 never been proved satisfactorily. Moreover it is not in question that 

 races of plants taken into unsuitable climates do degenerate rapidly 

 from uncertain causes, but that is quite another matter. 



The first question is to determine whether a given rogue has in it 

 any factor which is dominant to the corresponding character in the 

 typical plants of the crop. If it has, then we may feel considerable 

 confidence that these rogues have been introduced by accidental mix- 

 ture. The only alternative, indeed, is cross-fertilization with some dis- 

 tinct variety possessing the dominant, or crossing within the limits of 

 the typical plants themselves occurring in such a way that complemen- 

 tary factors have been brought together. This last is a comparatively 

 infrequent phenomenon, and need not be considered till more probable 

 hypotheses have been disposed of. If the rogues are first crosses the 

 fact can be immediately proved by sowing their seeds, for segregation 

 will then be evident. For example, a truly round seed is occasionally, 

 though very rarely, found on varieties of pea which have wrinkled seeds. 

 I have three times seen such seeds on my own plants. A few more were 

 kindly given me by Mr. Arthur Sutton, and I have also received a few 

 from M. Philippe de Vilmorin — to both of whom I am indebted for 

 most helpful assistance and advice. Of these abnormal or unexpected 

 seeds some died without germinating, but all which did germinate in 

 due course produced the normal mixture of round and wrinkled, proving 

 that a cross had occurred. Cross-fertilization in culinary peas is exces- 

 sively rare, but it is certainly sometimes effected, doubtless by the leaf- 

 cutter bee (Megachile) or a humble-bee visiting flowers in which for 

 some reason the pollen has been inoperative. But in peas crossing is 

 assuredly not the source of the ordinary rogues. These plants have a 

 very peculiar conformation, being tall and straggling, with long inter- 

 nodes, small leaves and small flowers, which together give them a 

 curious wild look. "When one compares them with the typical culti- 

 vated plants which have a more luxuriant habit, it seems difficult to 

 suppose that the rogue can really be recessive in such a type. True, we 

 can not say definitely a priori that any one character is dominant to 

 another, but old preconceptions are so strong that without actual evi- 

 dence we always incline to think of the wilder and more primitive 

 characteristics as dominants. Nevertheless, from such observations as 

 I have been able to make I can not find any valid reason for doubting 

 that the rogues are really recessives to the type. One feature in par- 

 ticular is quite inconsistent with the belief that these rogues are in any 



