1893.] NATURAL SCIENCES OF PHILADELPHIA. 191 



in case of the glandular hairs of Braseuia peltata, especially so in 

 hairs from near the vegetative point. On these successive sheaths 

 may he frequently seen, as in fig. VI, S' & S", the next one appear- 

 ing before the preceding one is dissolved. Fig. VII represents the 

 apices of three such sheaths, the innermost always being the one last 

 formed. 



In accordance also with observations on similar organs of other 

 plants, the secretion and secreting organs are most thick on the 

 youngest and most tender parts as already described and represented 

 in fig. I. The activity of the hairs evidently decreases from the 

 punctum vegetationis backward, and ceases entirely on the older 

 fully-developed parts. The hairs, although they cannot dry up in 

 the manner usually to be observed on land plants, seem to die off 

 and finally disappear, as indicated in fig. IV, a cross section of an 

 older portion of the rhizome which no longer possessed any or, 

 perhaps, slight traces of the gelatinous coating. Fig. V represents 

 a surface view of the epidermis taken from about the same point 

 as the cross section represented in fig. IV. In fig. V the places 

 where the glandular hairs had once been active, are represented by 

 H. 



Fig. Ill, on the other hand, shows the great quantity of glands 

 which beset a petiole which is thickly coated with jelly, and the 

 more closely the vegetative point is approached, the more closely 

 the glands are packed together, in fact, as has been stated before, at 

 the points of greatest activity they are crowded to such an extent as 

 to leave no spaces between them. 



The glandular hairs of Brasenia peltata are then, as plant hairs 

 are very apt to be, transitory organs, disappearing in the course of 

 the development of the part which produces them. In function 

 they are no doubt comparable to the " Colleters " of Hanstein. 1 

 This name Hanstein applies to the more massive trichomes which 

 are found on the epidermis of leaves while still in the bud, and 

 secreting during that stage different substances, such as gum or gum 

 and resin, and by this means causing the parts to adhere to each 

 other and protecting them from unfavorable external agencies. This 

 active secretion must have been noticed by every one who has ever 

 observed the opening of the buds of the horse-chestnut, poplar, etc. 

 It may also be seen in the case of Salvia, Polygonum, Helianthus 

 and other herbaceous plants. 



1 DeBary, Vergleichende Anatomie, Leipzig, 1877, p. 104. 



