86 DROSERA ROTUNDIFOLIA. [Cuar. VI. 
moderately well inflected in 24 hrs., but began to re-expand 
after 48 hrs., and were fully re-expanded in 72 hrs., always 
reckoning from the time when the bits were first given. This 
substance, therefore, like fibrin, excites the leaves for only a 
short time. The residue left on the leaves, after they were 
fully re-expanded, was examined under a high power and 
found much altered, but, owing to the presence of a quantity 
of elastic tissue, which is never acted on, could hardly be 
said to be in a liquefied condition. 
Some areolar tissue free from elastic tissue was next 
procured from the visceral cavity of a toad, and moderately 
sized, as well as very small, bits were placed on five leaves. 
After 24 hrs. two of the bits were completely liquefied ; two 
others were rendered transparent, but not quite liquefied ; 
whilst the fifth was but little affected. Several glands on the 
three latter leaves were now moistened with a little saliva, 
which soon caused much inflection and secretion, with the 
result that in the course of 12 additional hrs. one leaf alone 
showed a remnant of undigested tissue. On the discs of the 
four other leaves (to one of which a rather large bit had 
been given) nothing was left except some transparent viscid 
fluid. I may add that some of this tissue included points of 
black pigment, and these were not at all affected. As a 
control experiment, small portions of this tissue were left in 
water and on wet moss for the same length of time, and 
remained white and opaque. From these facts it is clear 
that areolar tissue is easily and quickly digested by the 
secretion ; but that it does not greatly excite the leaves. 
Cartilage—Three cubes (>p of an inch or 1°27 mm.) of 
white, translucent, extremely tough cartilage were cut from 
the end of a slightly roasted leg-bone of a sheep. These 
were placed on three leaves, borne by poor, small plants in 
my greenhouse during November; and it seemed in the 
highest degree improbable that so hard a substance would be 
digested under such unfavourable circumstances. Neverthe- 
less, after 48 hrs., the cubes were largely dissolved and 
converted into minute spheres, surrounded by transparent, 
very acid fluid. Two of these spheres were completely 
softened to their centres; whilst the third still contained a 
very small irregularly shaped core of solid cartilage. Their 
surfaces were seen under the microscope to be curiously 
marked by prominent ridges, showing that the cartilage had 
been unequally corroded by the secretion. I need hardly say 
