126 



SCIENTIFIC AGRICULTURE 



December, 1921. 



wiieluiiiig majority of plants possessinp: 

 the usual central leaf markings. Had the 

 absence of markings been a dominant 

 character, it is apparent that the majority 

 of the plants in the progenies would have 

 been without markings. 



Plants with basal markings were first 

 observed by Kajanits in 1911, viz. : in the 

 progenies of two plants, one of which had 

 normal central markings and the other no 

 markings at all. The plant having cen- 

 tral markings gave when open-fertilized 

 the following progeny. 



Plants with central markings ... .75 



" " basal markings 21 



' ' without markings 11 



Total 107 

 The plant having no markings produced 

 a progeny as follow : — 

 Plants with central markings ... .40 



" " basal markings 5 



" without markings 11 



Total 56 

 Kajamis concludes (2. p. 43) that, as in 

 the first mentioned case the segregation 

 appears to take place after the di-hybrid 

 formula, there are two factors for the 

 markings of the leaves, viz. : one for cen- 

 tral markings and another for the basal 

 one. He further concludes that central 

 marking is dominant over basal. 



Gmelin (2. p. 425-430) investigated tjie 

 hereditary' character of leaf markings by 

 studying the progeny of both open-fer- 

 tilized and controlled fertilized plants. He 

 found that of 20 open-fertilized mother 

 plants of the so-called Eoosendaal clover, 

 five produced a small percentage of plants 

 without leaf markings. Among a total of 

 953 descendants from the twenty mother 

 plants, only 23 were lacking leaf mark- 

 ings, or about 2.4 per cent. Of eleven also 

 open-fertilized mother plants of so-called 

 Maas <ilover. five gave a small number of 

 plants having no leaf markings. Among 

 a total of 527 descendants from the eleven 

 raotlier plants 25,or about 4.7 per cent, 

 showed no signs of leaf markings. These 

 figures evidently indicate the d^)minant 

 character of presence of markings. 



Particularly interesting are Gmelin'^ 

 studies of the leaf markings on controlled- 

 fertilized material. In these studies, he 



worked with pairs of two plants, each 

 pair isolated together and then cross- 

 fertilized. The various pairs fall into 

 three groups, viz. : 



Group 1 : composed of pairs of which the 

 one component had leaf markings, the 

 other not. 

 Group 2 : composed of pairs of which botli 

 components were without leaf mark- 

 ings! 

 Group 3 : composed of pairs of which both 

 components possessed leaf markings. 

 The first group contained one pair of 

 plants of Roosendaal clover and one pair 

 of plants of Maas clover. The two com- 

 ponents of each of the pairs were inter- 

 crossed, with the following results : 

 Roos. cl. without markings x Roos. cl. 

 with markings ; progeny 48 plants, 

 all with markings. 

 Roos. cl. with markings x Roos. cl. with- 

 out markings; progeny 48 plants all 

 with markings. 

 Maas cl. without markings x Maas cl. with 

 m'arkings ; progeny 44 plants of which 

 26 with and 18 without markings. 

 Maas cl. with markings x Maas cl. without 

 markings; progeny 46 ^plants, of 

 which 27 with and 19 without mark- 

 ings. 

 From these results several conclusions 

 may be drawn. In the first place it ap- 

 pears that, if two plants are inter-crossed, 

 their respective progenies will show the 

 same hereditary complexion. In other 

 words, in crossing two different types it 

 is immaterial whether the one or the other 

 is used as the female parent. Secondly, 

 presence of leaf markings is dominant 

 over its absence. Thirdly, the appearance 

 or non-appearance of the recessive char- 

 acter, i.e., lack of leaf markings in the 

 progeny depends upon the sexual com- 

 plexion of the parent having the dominant 

 character. In the case of the Roosendaal 

 clover pair, the plant with leaf markings 

 was evidently monozygous in respect to 

 the Mendelian factor or factors for leaf 

 markings; in the case of the !Maas clover 

 pair, the plant Avith leaf markings was 

 heterozj'gous. 



The second group contained four pairs 

 of plants, all without leaf markings. The 

 progeny of three of the pairs showed no 



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