84 Varietäten, Descendenz, Hybriden. 



Fernald, M. L. and H. St. John. The varieties of Hieracium 

 scahrum. (Rhodora. XVI. p. 181—183. Oct. 1914.) 



Contains as new the varieties leucocaule, tonsum and intonsum. 



Trelease. 



Leake, H. M., A preliminary note on the factors Control- 

 ling the ginning percent of Indian cottons. (Journ. of 

 Genetics. IV. p. 41—47. 1914.) 



The cotton crop as harvested consists of the Ünt in which ihe 

 seeds are imbedded. This seed-cotton is then ginned, by which 

 process seed and lint are separated. The ginning percent as here 

 used may be defined as the number of pounds of lint obtained from 

 100 Ibs. of seed-cotton. 



The object of the present work was to determine whether the 

 fluctuations in the ginning percent (which is evidentl}^ not a simple 

 character) can be accounted for by that of the characters 1. volume 

 of seed 2. number of fibres arising from a Single seed 3. weight 

 of individual fibres. From a series of 232 samples the author con- 

 cludes that the ginning percent cannot be directly measured from 

 any one of the characters here dealt with. But a consideration of 

 the partial correlation coefficients shows that the four characters 

 1. volume of seed 2. number of fibres from a Single seed 3. weight 

 of individual fibres 4. ginning percent, form a closely interrelated 

 group in which Variation in any one character is fully accounted 

 for by Variation in one or other of the three. Further, of the three 

 characters by which the ginning percent may be affected, onlj^ 

 one — the number of fibres per seed — has any marked effect on 

 the ginning percent. Thus there is here definite proof that the gin- 

 ning percent is a complex character; and the determining cause of 

 variations in it must be sought indirectly through the effect on the 

 other three. W. Neilson Jones. 



Wheldale, M., Our present knowledge of the chemistr}'- 

 ofthe Mendelian factors for flo wer -colour. (Journ. of 

 Genetics. IV. 2. p. 109—129. 1 col. pl. 1914.) 



The present paper attempts to State the extent of our knowledge 

 regarding the chemical mechanism underlying the Mendelian fac- 

 tors for flower-colour. 



The author's own work is chiefly in connection with Antirrhi- 

 nmn vnajus. The genetical Constitution of some seven colour varie- 

 ties of A. ifiajus are referred to. The ivory and j^ellow pigments 

 prove to be flavones: the white variety contains no flavone. 



The flavones responsible for the ivory and yellow pigments are 

 apigenin and luteolin respectively, the former having one hydroxyl 

 group in the side ring, the latter two in the ortho position. 



The difference in the ivory and yellow varieties is regarded 

 as being due to the protoplasm producing in the one case a mono- 

 and in the other di-hydroxy benzoic acid from which the respective 

 flavones are then synthesized. The anthocyanin pigments, it is sug- 

 gested, are oxidation or condensation products of flavone, or both. 

 This is supported by examination of red and magenta pigments 

 isolated from Antirrhimim: analysis shows that they both contain 

 a higher percentage of oxygen than the flavones, while their mole- 

 cular weights are two or three times as high. The work of other 



