November, 1910k] 



423 



Scientific Agriculture. 



to return to the previous example, there 

 is no dominance in regard to the face 

 colour ; if the white and black determin- 

 ants are both present, the face is speck- 

 led. In regard to wool colour, however, 

 we have reason to believe that white is 

 dominant to black, and that the appear- 

 ance of black-woolled sheep in a pure 

 race of white sheep is due to the acci- 

 dental mating of two individuals each 

 carrying recessive black determinant. 

 Similarly, black is apparently dominant 

 to red in the Angus and Galloway breeds 

 of cattle, while in other breeds, if botli 

 black and red are present, we get the 

 brindled marking. 



In stating the method in which new 

 combinations are produced it has been 

 said that the offspring of the first 

 crosses, if sufficiently numerous, will 

 include the desired result. The proviso 

 must not be lost sight of, for it points 

 to the most formidable obstacle in the 

 way of researches into the laws of 

 heredity in domestic animals. If we 

 set out to modify two characters of an 

 animal, it can be shown that there is 

 only ono chance in sixteen that the 

 second generation will contain what we 

 want; if we wish a new combination of 

 three characters, the chauces are one 

 in sixty four ; each additional factor 

 multiplies the chances against by four. 

 Next, we have the complexity resulting 

 from the separation of the sexes in 

 animals. It will be readily understood 

 why plants provide the best material 

 for such reseaiches ; by self-fertilising a 

 plant, we can ensure that both the 

 male and the female elements are of 

 the same constitution, both visually 

 and latently, and the breeding of the 

 large numbers required presents no 

 great difficulty. But all these obstacles 

 to the application of the new methods 

 to the larger animals appear insigni- 

 ficant when it is pointed out that the 

 territory so far explored by the followers 

 of Mendel is really, from an economic 

 point of view, a very limited one. For 

 the laws of inheritance of such indefinite 

 characters as size, shape, fertility, 

 rigour, are still unknown. If, for ex- 

 ample, we select such an important 

 problem as the combining in one breed 

 of a high standard of beef and milk 

 production, the indefiniteness which 



characterises these points, as contrasted 

 with, say, horns and no horns, renders 

 the application of Mendelian methods 

 to the problem almost inconceivable, 

 not to speak of the impossibility of test- 

 ing males for milk-producing capacity. 



The Mendelian does not depreciate 

 the value of the time honoured method 

 of selection in attacking such problems ; 

 he only hopes to discover the laws which 

 govern the variations which the breeder 

 has hitherto left very largely to chance ; 

 moreover, he suspects the improvement 

 in any desired direction which can be 

 attained by selection within pure breeds, 

 lies within very narrow limits, which 

 in most cases have already been reached. 

 There is another important economic 

 principle in stockbreeding which, so far, 

 has nc Mendelian explanation. It is 

 well-known that continued inbreeding 

 leads to loss of vigour, a fact which, 

 perhaps accounts for the superiority of 

 the cross-bred for fattening purposes. 

 Darwin's dictum that "Nature abhors 

 perpetual self-f ertilisation " is of no 

 higher scientific value that the mediseval 

 "Nature abhors a vacuum' is an ex- 

 planation of the rise of water in a pump. 

 That all the offspring of incestuous 

 unions are not degenerate is proved by 

 Co^sar E wart's experiments on goats ; 

 cereals maintain their fertility in spite 

 of the fact that they are perpetually 

 self-fertilised. The discovery of physical 

 laws behind these facts is imperative, 

 if further progress in the science of 

 heredity is to be hoped for ; that in its 

 present condition the science is not 

 in a position to give much help to the 

 breeder of farm animals is sufficiently 

 evident from what has been said. New 

 facts, however, may profoundly modify 

 current views, and lead to discoveries 

 of more economic value. What is 

 wanted is the opportunity and the 

 means to carry out experiments on a 

 large scale, such as would be afforded by 

 the foundation of an institute (on the 

 model of that recently established at 

 Merton through the liberality of the 

 late Mr. John Innes) provided with a 

 staff of experts, both practial and 

 scientific, and liberally endowed with 

 the funds which such expensive investi- 

 gations necessitate. 



