Miscellaneous. 



536 



[December, 19M), 



variation between plots on an acre was 

 35 per cent.— a much greater difference 

 than the breeder of wheat expects to get. 

 Lehmann found differences varying from 

 to 300 per cent., and further that on 

 many plots the difference was increased 

 or diminished according to the season. 

 He proposes to use in his work with 

 fertilisers only the plots that give uni- 

 form results for at least two similar 

 reasons, a method that he calls standard- 

 isation. In this country agronomists 

 have used mainly the system of check 

 plots, a system which it now appears 

 may be absolutely misleading. Indeed, 

 a study of the check plot records in 

 various experiments shows that they 

 vary in just the same way that Lehmann 

 found his plots to vary- 

 Some American agronomists are em- 

 ploying the method of duplicate plots, 

 a plan that is rapidly growing in favour. 

 The number of duplications for the most 

 accurate work will necessarily vary ac- 

 cording to the evenness of the soil, four 

 to six duplications apparently being 

 necessary for very accurate results even 

 on fairly uniform soil. The subject is, 

 however, one that needs much additional 

 investigation, as the disturbing effects 

 of soil inequalities have evidently been 

 greatly underestimated. 



The results of plant breeding seem 

 likely, therefore, to have a profound 

 effect on agronomy as a whole, demand- 

 ing as it does both the most accurate 

 plot methods to determine relative yields 

 and a much more extensive knowledge 

 of our crop plants — the material with 

 which breeding must work. 



There is still another botanical method 

 that needs to be brought more intensive- 

 ly into agronomy — namely, the method 

 of pure cultures, which has brought so 

 great results in our knowledge of the 

 lower plants, It is this method that 

 enabled Mendel to discover the pheno- 

 mena that bear his name. Practical 

 plant breeders now genei'ally use the 

 plant-to-row or centgener method in 

 comparing the value of selected plants. 

 It is probably due to the non-use of such 

 careful methods that the origin of most 

 cultivated varieties is so obscure. In 

 many cases, a so-called sport or hybrid 

 turns out to be a well-known thing— in 

 all probability the result of a stray seed. 

 This is perhaps unavoidable, as the busi- 

 ness of the seed grower does not readily 

 lend itself to accurate scientific methods. 



Of late years our knowledge concern- 

 ing hybrids and the behaviour of charac- 

 ters in hybrids has increased, greatly due 

 to the rediscovery of Mendel's laws and 

 the immense amount of splendid investi- 

 gation which was thus stimulated. No 



more admirable body of work has ever 

 been done than that of the Mendelists. 

 If it continues as rapidly as it has we 

 may soon expect to know approximately 

 the extent to which hybridising is a 

 factor in the evolution of our cultivated 

 plants. While the methods of the prac- 

 tical breeder are perhaps necessarily 

 different or at least less accurate than 

 those of the scientific breeder, yet the 

 results of the scientific work are already 

 having profound effect on practical 

 methods. 



Without at all minimising the fruitful 

 results and greater promises of Mende- 

 lian investigations, the subject of sport9 

 is to both the breeder and the evolutionist 

 a matter of far greater moment. Cer- 

 tainly our knowledge concerning sports is 

 far less than that of hybrids. The more 

 enthusiastic Mendelists have evinced 

 some disposition to deny the existence 

 of "sports" in the commonly accepted 

 sense, and would explain them as the 

 result of some previous, even remote, 

 cross. But it is self-evident that hybrids 

 presuppose the existence of two different 

 things to cross, and sporting is supposed 

 to be one method by which a distinct 

 form more or less suddenly arises. Let 

 us examine carefully the evidence regard- 

 ing " sports." Bud sports, where one 

 branch of a plant is different from the 

 rest, occurring commonly as variations 

 with differently covered flowers, differ- 

 ent leave?, etc., are well known. There 

 can be no question as to the origin of 

 the sport here, though to be sure the 

 parent plant may be a cross or hybrid. 

 Seed sports are supposed to arise in an 

 analogous manner. The general occur- 

 rence of certain types of assumed sports 

 is strong argument in favour of their 

 actuality. Thus, white-flowered variants 

 are known in practically all plants with 

 normally red or blue flowers ; cut-leaved 

 varieties are very common and generally 

 distributed among the plant families ; 

 dwarf varieties occur in numerous spe- 

 cies, as do smooth varieties in hairy spe- 

 cies and vice versa. The logical inference 

 is that the difference is due in each case 

 to the same underlying cause. In some 

 eases the origin of these sports is a matter 

 of definite record, as in the case of the 

 cut-leaved form of Chelidonium majus, 

 the globose-plodded form of shepherds 

 purse and others. In the whit^-flowered 

 form of bleeding heart— its only variant 

 — previous hybridisation seems clearly 

 excluded by the absence of any related 

 form that will cross with it. Many such 

 cases can be enumerated and tend to 

 uphold clearly the gardner's idea of 

 sports. But what are these sports, and 

 how do they arise? Apart from the 



