December, 1921. 



SCIENTIFIC AGRICULTURE 



127 



leaf iiiarkinf?s at all, while tlie progeny of 

 the fourtii pair consisted of 16 plants with 

 markings and 31 without. In the latter 

 ease, however, Gmelin is inclined to think 

 that the character of leaf marking was 

 present in at least one of the parents, al- 

 though in such an obscure form that it 

 escaped detection when the parent plants 

 were selected as i-epresentatives of types 

 having no leaf markings. 



The third group contained sixteen pairs 

 of plants, all Avith leaf markings. Of 

 these, only three produced a progeny in 

 which plants without leaf markings Avere 

 present. The ratio of plants with and 

 without leaf markings obtained from the 

 said three pairs being 40 :6. 32 :15, and 

 40:8 respectively, Gmelin concludes that 

 there are at least two Mendelian factors 

 for leaf markings in Red Clover, a fact 

 which, indeed, may a priori be considered 

 likely in vicAV of the great variation found 

 in th^ character in questi<)n. 



Concerning the practical application of 

 the results of the investigations briefly 

 related, it may be added that Gmelin suc- 

 ceeded in developing several races of 

 Maas clover Avhich all, however different 

 in other respects, are characterized by 

 lack of leaf markings (3. p. 1).* 



Polyphylly and Fasciation. 

 ..Occurrence of Polyphylly: — While the 

 I'ed clover leaf generally is trifoliate, i.e., 

 is composed of three leaflets, individuals 

 are frequently found, as is well known, in, 

 Avhich a smaller or greater number of the 

 leaves are polyphyllous, i.e., are composed 



"In a previous paragraph it has been ex- 

 plained that the presence of leaf mark- 

 ings is associated Avith a partial destruc- 

 tion of the chlorophyll in the palisade 

 cells underlying the marked areas. As 

 the palisade cells constitute the chief 

 assimilating tissue of the. leaves, it stands 

 to reason to surmise that leaA-es Avith 

 markings assimilate less than lea\'es 

 Avhich are Avholly green, and that the 

 larger and more conspicuous the mark- 

 ings are, the more is the assimilatory 

 function of the leaves impaired (Kajanus 

 5. p. 2-3). The dcA^elopment of races or 

 varieties lacking leaf markings is there- 

 fore not only of theoretical interest, but 

 also of practical importance. 



of more than three leaflets. Individuals 

 ai-e also found in Avhich leaves Avith less 

 than t,iiree leaflets occur. In the case 

 of polyphyllous plants, the number of leaf- 

 lets may vary from four to nine, the 

 general rule being that the greater the 

 number of leaflets to a leaf, the rarer its 

 occurrence. 



As an example illustrating the relative 

 frequency of the occurrence of leaves 

 other than trifoliate may be mentioned a 

 case investigated by Kajanus. Kajanus 

 dp. 64-66) found, in 1910, a specimen 

 having eight 4-foliate and six 5-foliate 

 leaA^es. The seed of this plant Avas har- 

 vested separately and subsequently soAvn. 

 A total of 131 plants Avere obtained 

 of Avhich 71 Avere more or less poly- 

 phyllous and 60 normal, i.e., 3-foliate. 

 The frequency of polyphylly in the 

 71 plants Avas further studied and 

 was found to vary considerably. tSome 

 plants had less than one per cent 

 polyphyllous leaves, while others had 

 betAveen sixiy and seventy per cent. A 

 total of 15,897 leaves from the 71 plants 

 Avere found to have a number of leaflets 

 as f olloAvs : 



12 3 4 5 6 7 



fo. fo. fo. fo. fo. fo. fo. total. 



Xo. 19 57 14348 1089 341 33 10 15897 



p.c. .12 .36 90.25 6.85 2.15 .21 .06 100 



In connection Avith the occurrence of 

 polyphyllous leaves in a given plant, 

 Kajanus (1. p. 67) further made the ob- 

 servation that 3-foliate leaves appear 

 first ; later appear 4-foliate, 5-foliate, etc.. 

 until the maximum development of poly- 

 phylh' has been reached, after Avhich a 

 gradual return to leaves with a smaller 

 number of leaflets takes place. The latest 

 leavies thus become 3-foliate, or in cases, 

 even 2 or 1-foliate. 



Formation of Polyphyllous Leaves:^ 

 Polyphyllous leaves are developed from 

 typical 3-foliate leaves by the splitting, 

 on an early stage of development, of one 

 or more of the three original leaflets. 

 This splitting, hoAA-ever, may take place in 

 a different manner in different cases. 

 Thus, Tamm.es (1), and Kajanus (4) dis- 

 tinguish between tAvo kinds of splitting, 

 Anz. : lateral and median. In the first 

 case the splitting takes place laterally of 



