418 UTRICULARIA NEGLECTA. Cuar. XVIL 
In this latter case, as soon as the pressure is relaxed, air 
is drawn in, and the bladder recovers its proper form. 
If it is now placed under water and again gently 
pressed, minute bubbles issue from the orifice and 
nowhere else, showing that the walls of the bladder 
have not been ruptured. I mention this because Cohn 
quotes a statement by Treviranus, that air cannot be 
forced out of a bladder without rupturing it. We may 
therefore conclude that whenever air is secreted within 
a bladder already full of water, some water will be 
slowly driven out through the orifice. Hence I can 
hardly doubt that the numerous glands crowded round 
the orifice are adapted to absorb matter from the 
putrid water, which will occasionally escape from 
bladders including decayed animals. 
In order to test this conclusion, I experimented with various 
solutions on the glands. As in the case of the quadrifids, salts 
of ammonia were tried, since these are generated by the final 
decay of animal matter under water. Unfortunately the glands 
cannot be carefully examined whilst attached to the bladders 
in their entire state. Their summits, therefore, including the 
valve, collar, and antenne, were sliced off, and the condition 
of the glands observed ; they were then irrigated, whilst beneath 
a covering glass, with the solutions, and after a time re-ex- 
. amined with the same power as before, namely No. 8 of Hart- 
nack. The following experiments were thus made. 
As a contro] experiment solutions of one part of white sugar 
and of one part of gum to 218 of water were first used, to see 
whether these produced any change in the glands. It was 
also necessary to observe whether the glands were affected by 
the summits of the bladders having been cut off. The summits 
of four were thus tried; one being examined after 2 hrs. 30 m., 
and the other three after 23 hrs.; but there was no marked 
change in the glands of any uf them. 
Two summits bearing quite colourless glands were irrigated 
with a solution of carbonate of ammonia of the same strength 
(viz. one part to 218 of water), and in 5 m. the primordial 
utricles of most of the glands were somewhat contracted; they . 
were also thickened in specks or patches, and had assumed a pale 
