932 Summary of Agricultural Experiments, [feb., 



of roots was so slight that the dry matter in ordinary roots must be 

 regarded as of practically the same feeding value. 



The value of the roots for practical purposes must therefore be 

 calculated according to their dry matter, and the class of root to be 

 selected for cultivation must be that which is found to give in this 

 respect the biggest crop. It must also fulfil requirements as to keeping 

 qualities and also as regards harvesting. 



Inheritance in the Potato (Journal of Genetics, Vol. I. No. i). — The 

 new Journal of Genetics, edited by Mr. Bateson and Prof. Punnett, 

 contains an interesting and valuable article on inheritance in the 

 potato. The author is Dr. Salaman, a new worker in the field of 

 heredity, who has devoted the last four years to the study of heredity 

 in the potato. The result may be regarded as a new triumph for the 

 Mendelian theory ; for Dr. Salaman has shown that the inheritance of 

 such characters as shape, depth of eye, and colour of skin — all characters 

 of economic importance — follow Mendelian lines. Further, there are 

 indications that susceptibility and immunity to disease are probably 

 Mendelian "factors," and may yield to the treatment which, in the 

 hands of Professor Biff en, has been so successful in producing a rust- 

 proof wheat. The problems to which the discoveries of Dr. Salaman 

 give rise are, however, of a more complex character than in the case 

 of wheat. It is well known that the seed of the domestic varieties of 

 potato does not come true ; in other words, these varieties are hybrids 

 in the Mendelian sense. The importance of Dr. Salaman 's work lies in 

 the fact that if the various characters — such as the colour of the tuber — 

 in which the seedlings differ from one another be examined, it is found 

 that they can be arranged in pairs, and the inheritance of each pair 

 is independent of the inheritance of the others. For example, if two 

 varieties possessing shallow eyes be crossed, the seedlings of the cross 

 will all have shallow eyes ; but if deep-eye be crossed with shallow-eye, 

 either one-half of the offspring will be deep-eyed and one-half shallow- 

 eyed, or all the offspring will be deep-eyed, showing that deep-eyes and 

 shallow-eyes are a pair of Mendelian characters, of which the former 

 is dominant. 



The feature of Dr. Salaman 's work which is of the greatest 

 economic importance is found in his experiments on Solanum 

 tuberosum, a variety of potato which is useless for domestic purposes, 

 but which is believed to be absolutely immune to potato disease. Seed- 

 lings raised from this potato are apparently of two kinds, one susceptible 

 to disease and the other immune. If it should prove that susceptibility 

 and immunity are Mendelian characters which segregate, then the pos- 

 sibility of producing a potato immune to disease and at the same 

 time fit for domestic use at once emerges. It is needless to say that 

 the economic advantages of such a variety would be as incalculable as 

 the losses which result from the liability to disease of practically all 

 the domestic varieties now under cultivation. 



A Russian Method of Corn Cultivation. — The experiments mentioned 

 in this Journal (December, 1909) as having been carried out in Germany 

 with a view to testing the efficacy of the method of corn cultivation 

 advocated by M. Demtschinsky, have been continued during 1910, and 

 the results are reported in the Mitteilungen der Deutschen Land.- 

 Gesellschaft (November 19th, 1910). 



