356 



SCIENCE. 



[Vol. XXII. No. 569 



aperture, they must either be decomposed inside the cell, 

 or there must also be an aperture at the lower end, or 

 that the particles should be forced out (as is done by the 

 amffiba). There may, indeed, be such a basal aperture 

 which it would be difficult or impossible to distinguish. 

 But close examination of the base of the root hairs indi- 

 cates that, although they may originate in an epidermal 

 cell, the internal part of the hair seems to communicate 



no real difficulty here, for it is known that decomposition 

 takes place within the plant, and it may as well be done in 

 a hair cell as any other cell. 



Having now considered the literature on the subject, 

 observations made on the aperture may be returned to. 

 That there is a definite formation of an aperture with lips, 

 I have satisfied myself m regard to a large number of root 

 hairs, illustrations of which are given here, and it will be 



Mangold— Branelied. 



Particles seemed drawn 

 w-thin and hair grown 

 round it. Hole on side. 



Turnip— Branched. 



UNUSUAL FO ;MS OF ROOT HAIRS. (Rarely occurring in the above 

 plants.) 



Grass— Particles freqifently seen inside 

 occupying line of inner tube. 



-A peculfarly formed hair. A 

 times, when hole large, particle 

 may be seen lying on lip. 



When hairs are allowe 1 to dry 

 under the object glass they shrivel 

 up and often discharge contents, 

 and this discharge is at the tip. 



When litmus solution is passed 

 under object glass it seems not to 

 affect outer tube, which remains 

 greenish, while inner tube becomes 

 tinted, hence the coluring matter 

 seems to pass nut through outer 

 membrane, but by the hole. 



In one case was seen? very dis- 

 tinctly a p ece of matter half way 

 into the tube of Pea root hair, 

 which is large; the darker tint of 

 the half lying outside indicated, H^, 

 well as the rim of hole, that the ' 

 other half was inside. 



ENTRANCE OF PARTICLES INTO APERTURE. 



53*r 



ACTU.\L Number in Field. Number Per Cent. 



Minute. Small, Medium. Large. Minute. Small. Medium. Large. 



Apatite 43 17 3 43 65 25 4 6 



Slag 13 2) 4 3 32 50 10 S 



S. B. flour no 15 3 2 86 11 2 i 



Coprolite 56 35 8 4 56 34 7 3 



STATE OF DIVISION OF MANURES EFFECTIVE ON PLANTS. (Apative— crystalline— only slightly so.l 

 Shi wing that in these manures there are particles so minute as to be able to pass mto aperture of root hairs. 



with the deeper tissue, or possibly with the vascular tis- 

 sue. Thus in examining the root hair of a carrot, the 

 faint bluish-grey appearance of the central tube was seen 

 to be continuous with the deeper tissue, though whether 

 entering into a vessel, or simply passing between the 

 cells, could not be distinguished. This relation of the hair 

 with the deeper tissue is supported by the origin of hairs 

 as described by Schwartz and Duchartre. But there is 



seen that they vary not a little, both in shape and posi- 

 tion, being usually a minute circular hole at the extreme, 

 and more or less tajsered, end of the inner tube, with, of 

 course, a correspondingly larger rim in the outer tube; 

 but sometimes the opening is transveri^e, sometimes not 

 quite at the tip, or, rather, the tip seems half curved, mak- 

 ing the aperture appear slightly at one side, and the tip 

 to appear like a lip or knob. 



