272 DROSOPHYLLUM LUSITANICUM. — [Cuar. XV. 
bell-glass with its inner surface and support thoroughly 
wetted, there was no loss by evaporation, and so much 
secretion was accumulated in the course of a day that it ran 
down the tentacies and covered large spaces of the leaves. 
The glands to which the above named nitrogenous 
substances and liquids were given did not, as just stated, 
secrete more copiously ; on the contrary, they absorbed their 
own drops of secretion with surprising quickness. Bits of 
damp fibrin were placed on five glands, and when they were 
looked at after an interval of 1 hr. 12 m., the fibrin was 
almost dry, the secretion having been all absorbed. So it 
was with three cubes of albumen after 1 hr. 19 m., and with 
four other cnbes, though these latter were not looked at 
until 2 hrs. 15 m. had elapsed. The same result followed in 
between 1 hr. 15 m. and 1 hr. 30 m. when particles both of 
cartilage and meat were placed on several glands. Lastly, a 
minute drop (about 545 of a minim) of a solution of one part 
of nitrate of ammonia to 146 of water was distributed between 
the secretion surrounding three glands, so that the amount 
of fluid surrounding each was slightly increased ; yet when 
looked at after 2 hrs., all three were dry. On the other 
hand, seven particles of glass and three of coal-cinders, of 
nearly the same size as those of the above-named. organic 
substances, were placed on ten glands; some of them being 
observed for 18 hrs., and others for two or three days; but 
there was not the least sign of the secretion being absorbed. 
Hence, in the former cases, the absorption of the secretion 
must have been due to the presence of some nitrogenous 
matter, which was either already soluble or was rendered so 
by the secretion. As the fibrin was pure, and had been well 
washed in distilled water after being kept in glycerine, and 
as the cartilage had been soaked in water, I suspect that. 
these substances must have been slightly acted on and 
rendered soluble within the above stated short periods. 
The glands have not only the power of rapid absorption, 
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 
