448 Lloyd : Anatomy of Chrysoma pauciflosculosa 



while the terminal cell maintains its shape and contents. (Fig. 3^.) 

 In type this form of hair agrees with that described by Vesque 

 (/. c.) which he found at the base of the heads of Chrysantliemitm 

 coronavium. The contour differs however. Occasionally one finds 

 such a hair composed of but one row of cells (Fig. 4). In all 

 cases so far observed the two series of cells, when two are present, 

 arise from two neighboring cells of the leaf, a fact which leads to 

 the view that we have before us a case of concrescence. This must 

 however be verified by a study of their development. 



The whip hairs (Fig. 5), on the other hand, are quite different 

 in form and function. They are composed of one series of four 

 cells. The basal cell is lenticular, with or without a projecting 

 portion. The second is a slender stalk-like cell ; the third a thicker 

 and somewhat longer cell, supporting at its outer end a long lash 

 cell, four to five times as long as the rest of the hair. At the base of 

 the lash cell is a bulbous enlargement upon which the lash is set ob- 

 liquely, as occurs in similar hairs in Carduns lanccolatits (Vesque, 

 /. c). The lumen of the lash cell is almost obliterated except toward 

 and at the base, and the thickened wall is composed of cellulose, with 

 a very thin layer of cuticle which extends over the whole hair and 

 is continuous with the cuticle of the leaf. The protoplasmic con- 

 tents are plainly seen in all the cells of the hair except the lash 

 cell, from which they appear to be absent in maturity. The whip 

 cells, the lash of which is somewhat curled, usually protrude out 

 of the sulcus and their slender ends lie upon the exposed leaf sur- 

 face. They occur in greatest numbers at the juncture of the sulci. 



When one asks concerning the function of these hairs the an- 

 swer is more difficult for the whip cells than for the gland cells. 

 From the latter is exuded the gummy secretion which renders the 

 leaf more effectually protected against the loss of moisture. The 

 activity of secretion is resident chiefly, or probably entirely, in the 

 terminal cell, as is indicated by the accumulation of calcium oxa- 

 late. The whip cells occur, in cases so far as known, only as part 

 of a tomentose or arachnoid covering (Vesque, /. c). We may 

 regard them here as useless morphological members, or we may 

 ascribe to them some function, such as leading by capillarity the 

 gummy secretion out upon the leaf surface exposed to the air. 

 That this takes place there is no doubt, though that this is more 

 than an incidental phenomenon may be doubted. 



