330 



DISCOVERY 



fundamentals of Mendelism obscures the complexity 

 of the plant-breeder's task. He chooses two parents 

 for their desirable characters, crosses them, and 

 endeavours to secure from the progeny a form which 

 combines the best features of both. In a simple case 

 he obtains an Fo of, say, i,ooo plants without much 

 difficulty. Parents differing in four or five pairs of 

 characters will give a considerable diversity of types 

 in F,, and in all probability there will be a number of 

 more recondite parental differences which escape 

 observation and reinforce the complexity of the 

 inheritance. By what tests may the best forms be 

 detected ? Will the form which excels as a single 

 plant still be the best when millions of its descendants 

 are grown crowded together in the field ? Are the 

 best-seeming forms homozygous in all characters ? 

 These are the inevitable puzzles. Judgment and 

 experience can alone attempt to solve them. As yet, 

 unaided, pure science cannot assess the agricultural 

 characters of plants, particularly of single plants. In 

 principle it would be quite simple to sow the seed of 

 every F, plant and thus obtain an F3 family, and from 

 this the F^. Fg . . . could be grown. In every 

 generation there is increased material on which to base 

 judgment. This is all to the good, but increase in 

 material means increase in ground-space and, above all, 

 in time and attention. To prevent the accumulation 

 of impracticably great numbers of plants — and a single 

 plant of wheat may in five years give rise to 100,000 — 

 elimination must begin early and become more intense 

 in the successive generations. When some twenty 

 forms remain, a chessboard trial of yield is conducted, 

 tests of other characters — e.g. of baking quality in 

 wheat — are made, and usually only one form is finally 

 retained. This is tested against well-known forms on a 

 field scale, and if found to be an improvement on them, 

 is placed upon the market. The production of a really 

 satisfactory form on these lines must occupy not less 

 than ten years, and fifteen is the probable number. 

 Many new forms are brought to market with inadequate 

 testing in a far shorter period. They enrich the pro- 

 ducer — as do most " novelties " — have their short 

 day, and disappear. Others follow in monotonous but 

 profitable succession : the farmer is the victim. 



It is well known that the F^ plant may in some cases 

 be far more robust than either of its parents. This 

 so-called " hybrid vigour " is a complex phenomenon 

 and may be displayed only in height and abundance 

 of foliage, there being little or no seed produced. But 

 ingenious minds, arguing from these cases that the act 

 of artificial hybridisation is responsible for increased 

 " vigour," have conceived a new procedure. Two 

 plants of precisely the same form, and which normally 

 would produce seed by self-fertilisation, are artificially 

 crossed. From seed so obtained there grow plants 



called " regenerated " plants, and from these stocks 

 of " regenerated seed of existing forms " are placed 

 upon the market at enhanced prices. Such " regenera- 

 tion," if a real phenomenon, is at present unknown to 

 science. It is noteworthy that in a careful test of the 

 yielding capacity of a form of wheat from ordinary seed, 

 and from seed " regenerated " in the manner described, 

 there was absolutely no indication of yield increase 

 through " regeneration." 



" England's premier wheat " (or cabbage, etc.) 

 is the recommendation sometimes bestowed on a form 

 newly marketed. It is misleading. Our country, 

 small as it is, has many different soils, and is afflicted 

 by great annual climatic variations. No plant form, 

 among the common crop-plants, is every year, and in 

 every place, better than all the otheis. Instead of claim- 

 ing or attempting to breed this master-form, the aim 

 must be to ascertain as closely as possible the special 

 environmental features of the different parts of the 

 country and to find or breed the plant forms best 

 adapted to them. Of the known forms of wheat, 

 barley, potatoes, etc., none is better than all others 

 in every part of England, and in a single county one 

 form may excel in the east, a different one in the west. 



The Berber Tribes of 

 Morocco 



By E. Gurney Salter, Litt.D. 



" The world is a peacock, Morocco is its tail." 



So runs the native proverb, voicing the naive patri- 

 otism of those to whom " the world " probably means 

 at most Moslem North Africa, from east to west. 

 But, indeed, Moghreb-el-Aksa, the " farthest west " 

 portion of this world, with its natural beauty and rich 

 endowments, stirs the enthusiasm of European visitors, 

 now that the motor and the aeroplane are invading its 

 secular inaccessibility. 



In descriptions of the triumphant progress of French 

 colonisation in the Protectorate, or of the recent severe 

 reverses suffered by the Spaniards in their northern 

 zone, allusion is frequently made to " the tribesmen " 

 of Morocco, or tribes are mentioned by name. Raisuli's 

 stage-bandit career is nearly as well known as Captain 

 Macheath's.i But, in general, ideas about these tribes 

 are rather vague, and it is hoped that the present 

 article may throw a little light on some characteristics 

 of the Berbers, who are quite the most interesting, as 

 well as the enormously preponderating race in the 



1 Those readers who have witnessed the recent revivals of 

 The Beggar's Opera and PoUy will be well acquainted with 

 this delightful villain. 



