088 



KuPFER : Anatomy and Physiology 



The whip- hairs, too, seem to differ from the types of Vesque 

 in that they are also, as a rule, bicollateral. They are thus ap- 

 parently homologous with the gland-hairs. The early condition 

 of the two kinds of hairs is very similar, the only difference being 

 that the whip-hairs are from the beginning devoid of chlorophyl. 

 In the adult condition, however, they are entirely separated from 

 each other. The enormously enlarged end-cells have walls so 

 highly thickened that the cell-lumen is almost obliterated (/. j). 

 The developing whip-hairs arc cutinized almost from the start. 

 When fully formed they are also uniformly covered with cutin, 

 but there is a stage in their growth in which the base only of the 

 end-cells is surrounded by a collar of cutin, while the thickened 





Hairs of Baccharis geniUelloides. Fig. 4. (lland-bair. FiG. 5. Two whip-haiis. 

 Fig. 6, a, b. Developing whip hairs. 



cellulose wall of the upper part shows prominently above and 

 through it (/. 6 a and b). Probably the cell in its period of hy- 

 pertrophy breaks through its cutin covering, which is reestablished 

 after growth has ceased. The two whip-hairs often fail to 

 develop simultaneously, so that a pair is frequently found, one 

 of which is still in its prime, while the other consists of only 

 shriveled empty cells. As far as has been determined, new hairs 

 of either kind are not developed much below 5-6 cm. from the 

 tip. As some also drop entirely off, the hairs on the older por- 

 tions are very scattered and frequently consist of only the shriveled 

 cells. 



