334 MUSSEL CLIMBING. 
booty. Again it ascended, affixed another thread, then de- 
scended and affixed to the prey as before. Each thread, in 
sailor phrase, was made taut. After a good many threads 
had been in this manner attached, each being stretched tightly, 
and each pulling a little, the weight was seen to ascend a 
small fraction of an inch. Again the threads were increased, 
and again the weight ascended a little more, until at last, 
after incredible labor, perseverance and skill, the little en- 
gineer had the satisfaction of success; for its well earned 
booty, with one final, tiny jerk “brought up” at the desired 
spot. The explanation of all this is simple. Suppose we take 
a cord of the material known by the ladies under the name 
elastic, and attach it to an ounce weight. If but very moder- 
ately stretched it would certainly pull at least a grain. Sup- 
posing it to do that, a second one would pull with equal force, 
and it would be but a simple estimate to determine how 
many threads would be required to raise the entire weight. 
But enough of this. Now for the mussel. 
Placed at the bottom of the aquarium, where it had been 
for a couple of days, it had succeeded in wiggling itself up 
to one of the glass sides of the tank. This coor plisbed 
it protruded its large foot, stretching it up as high on the 
glass as it could reach, this organ seemingly adhering very 
tightly. A little hole opened near the extreme forward end 
of the foot. This tiny hole was really the extremity of a 
folded or closed groove. Out of this a drop of white 
gluten, or mucus, not larger than the head of a pin, was 
exuded, and pressed against the glass. There was then a 
slight withdrawing of the foot, simultaneously with an un- ` 
folding, or opening of the groove, which contained, as if 
moulded there, the already completed delicate thread. This 
done, the partly contracted foot (not drawn into its shell at 
all, be it understood) was again extended, this time a little 
higher than before. The groove, or spinneret, was again 
closed, except the little opening on the surface of the foot, 
whence another little drop of mucus appeared, which also 
