182 lock: studies in plant breeding 



Correns has recently described dominance of the " hose-in- 

 hose" form over the normal type of flower in the cases of 

 Campanula and Mimulus. 



He has also put forward a formula to describe the phenomena 

 shown by the colours appearing when certain strains of Mir- 

 abilis are crossed together, which involves the interaction of 

 definite factors — factors which individually follow Mendel' s law. 



Castle has described at length the occurrence of Mendelian 

 phenomena on crossing strains of guinea-pigs and rabbits 

 which differed in the structural and colour characters of their 

 coats. 



Cudnot, continuing his experiments with mice, lias been 

 able to obtain the expected pure strains both of coloured mice 

 and of albinos carrying particular colour factors. The author 

 was however unable to obtain a pure race bearing the yellow 

 colour. CJCG x CJCG was expected to give in Fi : — 1 CJCJ : 

 2 CJCG : 1CGCG, but as a matter of fact this cross yielded 

 no pure yellow dominants at all (out of a total of 81 offspring). 

 No absolute explanation of this phenomenon is forthcoming, 

 but Cuenot suggests an analogy with the curious case described 

 by Correns in maize, in which the heterozygote crossed with 

 the recessive gave equality, whereas self -pollinated it gave 8-i 

 per cent, of the dominant type. 



Emmerson's results with kidney beans have been already 

 briefly referred to in Appendix 1. 



Hurst has published simple Mendelian results in the case of 

 peas, and the confirmation of Mendel's classical experiments 

 with these plants seems now to be complete. In the case of 

 experiments with poultry, this author has found certain ex- 

 ceptions to the usually simple Mendelian phenomena, and 

 these are to be made the object <>f further experiments. 



M'-Cracken has in all probability found simple dominance of 



a spotted type over the melanic form in the beetle Lina lappo- 



\nd Schuster has published results of crossing mice, 



whirh so far as they go are in complete accord with Mendelian 



expectation. 



