88 



The Journal of Heredity 



excess of the longs to the extent of 

 about 3:1. Since that date many other 

 cases of this peculiar association of 

 characters have been discovered in 

 other plants as well as in sweet-peas, 

 and certain generalizations have 

 emerged from the study of them. We 

 now know that if A and B represent 

 two factors respectively alternate to 

 their absence (a and b), then if the 

 original cross is of the nature AB x ab 

 the characters .4 and B will be more 

 or less completely associated in the F2 

 generation, so that of the four possible 

 classes AB : Ab : aB : ab the first and 

 the last will be the most numerous. If, 

 however, the original cross is of the form 

 Ab X aB, then of the four classes in F2 

 the AB one will be about twice as num- 

 erous as cither of the two classes Ab and 

 aB, while the class ab will be very rare. 

 Where A and B go into the cross in 

 association they tend to remain asso- 

 ciated in F2, whereas when they go into 

 the cross dissociated they tend to remain 

 dissociated in F2. This peculiar phe- 

 nomenon is not as yet pro])erly under- 

 stood, and it is with a view to obtaining 

 further knowledge that ex]3eriments are 

 being carried on at Merton by Professor 

 Bateson, and at Cambridge by Miss 

 Saunders with stocks, by R. P. Gregory 

 with primulas, and by the writer with 

 sweet-peas. 



Recent work, more especially that of 

 Morgan in America, has shown that 

 similar phenomena occur in animals, 

 and there is no doubt that a proper 

 understanding of them will eventually 

 turn out to be of much importance for 

 the breeder of plants and animals. It 

 is a matter of common observation 

 that characters seem at times to be 

 transmitted in bunches, as it were, from 

 one ])arent or other to the offspring, and 

 it is likely that in such cases we are 

 dealing with phenomena of the kind 

 just outlined. 



H.\TIi;SON's INSTITl'TION. 



The best-e(iuii)ped institute in Great 

 Britian for the study of genetics is 

 undoubtedly the John Innes Horti- 

 cultural Institution at Merton, near 

 London. Started in 1909 with funds 

 derived from ])rivate bequest, it was 



fortunate in securing Professor Bateson, 

 who left Cambridge in 1910, as its first 

 Director. Fortunately, also, its scope 

 is broad, and the ex]:)erimental work 

 undertaken is concerned with the unrav- 

 elling of the principles of inheritance in 

 the widest sense, apart from considera- 

 tions of direct economic return. Num- 

 bers of experiments are at present 

 being carried out by Professor Bateson 

 and his staff, principally with plants, 

 not the least interesting being a series 

 of experiments dealing with fertility 

 and sterility in fruit-trees. 



Besides Cambridge and Merton there 

 are several other places where genetic 

 research is being carried on. Mr. 

 Hurst, one of the pioneers in Mendelian 

 studies, has established an experimental 

 station at Burbage, near Leicester, 

 which aims at the production of eco- 

 nomically valuable varieties of plants, 

 and animals by working upon Mendelian 

 lines. Mr. Hurst is experimenting with 

 many different plants and animals, and 

 some of his most interesting experiments 

 concern horses, and aim at the produc- 

 tion of a pure race of steeplechasers — 

 i.e., of animals with a special aptitude 

 for hunting. 



Genetic research is also being carried 

 on by Professor Keeble at University 

 College, Reading, the chief material 

 investigated being primulas. But per- 

 haps the most interesting work from 

 this source is that dealing with the 

 chemical side of genetic problems. It 

 is well known that in i3rimulas there are 

 white flowers of two kinds — viz., those 

 dominant and those recessive to col- 

 ored. Professor Keeble and Dr. Arm- 

 strong have recently amplified the work 

 of Miss Wheldale and others, and have 

 demonstrated that these two forms of 

 white, though alike in a])iDearance, can 

 be distinguished by definite chemical 

 tests. Such work opens up a new and 

 important field of study, and it is 

 possil)le that as tliis l)ranch of knowl- 

 edge develoijs the genetic analysis of 

 l)lants and animals will be greatly sim- 

 plified by the substitution of direct 

 chemical tests for the elal^orate series 

 of lireeding-exi)eriments which are at 

 present necessary. 



