874 DROSOPHYLLUM LUSITANICUM. [Chap. XV. 



but likewise of secreting again quickly; and this latter habit 

 has perhaps been gained, inasmuch as insects, if they touch 

 the glands, generally withdraw the drops of secretion, which 

 have to be restored. The exact period of re-secretion was 

 recorded in only a few cases. The glands on which bits of 

 meat were placed, and which were nearly dry after about 1 

 hr. 30 m., when looked at after 22 additional hours, were 

 found secreting; so it was after 24 hrs. with one gland on 

 which a bit of albumen had been placetl. The three glands 

 to which a minute drop of a solution of nitrate of ammonia 

 was distributed, and which became dry after 2 hrs., were be- 

 ginning to re-secrete after only 12 additional hours. 



Tentacles Incapable of Movement. Many of the tall 

 tentacles, with insects adhering to them, were carefully ob- 

 served ; and fragments of insects, bits of raw meat, albumen, 

 &c., drops of a solution of two salts of ammonia and of 

 saliva, were placed on the glands of many tentacles; but not 

 a trace of movement could ever be detected. I also repeated- 

 ly irritated the glands with a needle, and scratched and 

 pricked the blades, but neither the blade nor the tentacles 

 became at all inflected. We may therefore conclude that 

 they are incapable of movement. 



On the Power of Absorption possessed hy the Olands. ^It 

 has already been indirectly shown that the glands on pedicels 

 absorb animal matter; and this is further shown by their 

 changed colour, and by the aggregation of their contents, 

 after they have been left in contact with nitrogenous sub- 

 stances or liquids. The following observations apply both 

 to the glands supported on pedicels and to the minute sessile 

 ones. Before a gland has been in any way stimulated, the 

 exterior cells commonly contain only limpid purple fluid; 

 the more central ones including mulberry-like masses of 

 purple granular matter. A leaf was placed in a little solu- 

 tion of one part of carbonate of ammonia to 146 of water 

 (3 grs. to 1 oz.), and the glands were instantly darkened and 

 very soon became black ; this change being due to the strong- 

 ly marked aggregation of their contents, more especially of 

 the inner cells. Another leaf was placed in a solution of 

 the same strength of nitrate of ammonia, and the glands 

 were slightly darkened in 25 m., more so in 50 m., and after 

 1 hr. 30 m. were of so dark a red as to appear almost black. 



