Daily Groicth-rings in the Cell Wall of Cotton Hairs. 543 



existence we had ventured to postulate. Knowledge of their real existence 

 must materially affect some of oui' views concerning the physical properties 

 of such hairs.* 



Material. 



The cotton material examined was chiefly of Egyptian origin, derived from 

 my pure strain No. 77, on which most of the previous physiological work has 

 heen standardised, but samples from other Egyptian strains and varieties, 

 together with cotton from other countries, have been used for check 

 purposes. 



In addition to mature cotton hairs (or " lint") and " fuzz," a small amount 

 of materialf pickled in acetic-absolute at all stages of growth had been 

 brought by the writer from Egypt, amounting to 12 fruits in all. The 

 growth-rings were shown by this equally well, in spite of five years and four 

 months immersion in the 30 per cent, alcoholic solution of glacial acetic. 



The seed-hairs of the cotton plant are of two kinds, the lint and the 

 " fuzz." In certain wild cottons we find various groupings of abnormally 

 long fuzz, short lint, or lack of differentiation between the two classes, which 

 facts, in conjunction with the data from genetic studies of cultivated varieties, 

 suggest that the two kinds of hair are intrinsically similar, in spite of the 

 great difference between them in external appearance. In the case of pure 

 strain No. 77, and most other Egyptian cottons, the fuzz-hairs are only about 

 15 mm. in length, clustered in two patches near the micropyle and base 

 respectively of the seed, and exhibiting a vivid but unstable emerald green 

 colour which fades to a rusty brown. Other cottons have fuzz which is 

 devoid of colouring matter, while others again always show a brown colour 

 without any precedent green. These colours occur also in the lint, a rare and 

 little-known rogue strain of American ((?. hirsutum ?) possessing vivid 

 emerald green lint which quickly fades on exposure. The genetic peculiari- 

 ties shown by various modifications, both of the seed-hairs proper, or lint, and 

 of the subsidiary seed-hairs, or fuzz, are closely similar ; this similarity 

 extends not merely to colour-factors, but also to the distribution of each upon 

 the seed-coat, and complex inheritance involving cryptomeres has been 

 demonstrated in the latter respect for both by the writer. 



The lint, or cotton fibre of common knowledge, is externally very unlike 

 the fuzz, attaining a length of nearly 60 mm. in some varieties, and carrying 

 a delicate brown colour at most, except in the green rogae above mentioned. 

 The diameter of the embryonic fuzz-hair is nearly twice that of the lint-hair, 



* Harrison, W., " Investigations on Textile Fibres," ' Eov. See. Proc.,' A, vol. 94, 

 p. 460 (1918). 



t 'Raw Cotton,' p. 175. 



