280 GLANDULAR HAIRS. [Chap. XV. 



absorb various fliiida or at least allow them readily to enter/ 

 it seems desirable to ascertain how far the glands of other 

 plants which are not specially adapted for capturing insects, 

 had the same power. Plants were chosen for trial at hazard, 

 with the exception of two species of saxifrage, which were 

 selected from belonging to a family allied to the Droseracec^. 

 Most of the experiments were made by immersing the glands 

 either in an infusion of raw meat or more commonly in a 

 solution of carbonate of ammonia, as this latter substance 

 acts so powerfully and rapidly on protoplasm. It seemed 

 also particularly desirable to ascertain whether ammonia 

 was absorbed, as a small amount is contained in rain-water. 

 With the Droseracese the secretion of a viscid fluid by the 

 glands does not prevent their absorbing; so that the glands 

 of other plants might excrete superfluous matter, or secrete 

 an odoriferous fluid as a protection against the attacks of 

 insects, or for any other purpose, and yet have the power of 

 absorbing. I regret that in the following cases I did not 

 try whether the secretion could digest or render soluble ani- 

 mal substances, but such experiments would have been diffi- 

 cult on account of the small size of the glands and the small 

 amount of secretion. We shall see in the next chapter that 

 the secretion from the glandular hairs of Pinguicula cer- 

 tainly dissolves animal matter. 



Saxifraga vmbrosa. The flower-peduncles and petioles of the 

 leaves are clothed with short hairs, bearing pink-coloured glandn, 

 formed of several polygonal cells, with their pedicels divided by 

 partitions into distinct cells, which are generally colourless, but 

 sometimes pink. The glands secrete a yellowish viscid fluid, by 

 which minute Diptera are sometimes, though not often, caught.* 

 The cells of the glands contain bright pink fluid, charged with 

 granules or with globular masses of pinkisli pulpy matter. This 

 nuitter must be protoplasm, for it is seen to undergo slow but in- 

 esaant changes of form if a gland be plaee<l in a dmp of water 

 and examined. Similar movements were observed after glands had 

 been immersed in water for 1. 3, 5. 18. and 27 hrs. Even after this 

 latter period the glnmls retainel llioir bright pink roloiir; and the 

 protoplasm within their cells did not appear to have become more 



' The distinction between tnie mncentlcnl .Toiirnnl,' May 1875> 



absorption and mero permeation, that he examined some dozens of 



or Imbibition, Is by no means plants, and In almost every In- 



clearly understood: see MUller's stance remnants of Insects ad- 



' I'hysloloKy.' Kng. translat. 18.38, herod to the leaves. So It Is, as 



vol. I. p. 280. I hear from a friend, with this 



* In the case of Saxifraga tri- plant In Ireland.' 

 Oaettflitet, Mr. Druce says (' Pbar- 



