52. LIVERPOOL BIOLOGICAL SOCIETY. 
conditions carefully noted. The experiments were repeated 
several times, the general results being that :— 
In the A jar, at the end of twelve hours all the specimens 
had crept up and were sticking to the under surface of the 
muslin; at the end of thirty-six hours, they had all fallen 
from the muslin, and were lying in various positions at the 
bottom of the jar; while at the end of the third day one or 
two were dead or dying, and most of the others seemed to 
be unwell. As the water in this jar had now gone bad, 
this experiment was not continued any further. Whether 
the sickly condition of the specimens in this jar was due 
merely to being kept immersed in sea-water for three days, 
or was caused by the water having become impure through 
the accidental (v.e. from some other, unknown, cause) 
death of one of the molluscs, it is impossible to say from a 
few experiments; but, at least, there is no doubt that the 
effect of putting closed up specimens of Littorina rudis 
into clean sea-water, out of which they cannot escape, is 
that they at once expand, become active, crawl as near 
as they can get to the surface of the water, and after 
remaining there for a time relax their hold and drop to 
the bottom. 
Fig. 3.—Experimental Jar containing Littorina kept in the water. 
In B (fresh water), all the specimens remained during 
the three days lying at the bottom of the jar in a tightly 
closed up condition, but were apparently perfectly healthy 
at the end of that time. The jar was kept under 
