980 THE AMERICAN NATURALIST. [VOL. XXXV. . 
deeper parts of the lagoon, reappearing at once near the sur- 
face as the temperature of the water began to rise. The small 
naids which form their food can be taken at all times through 
the winter from beneath the ice, so that so far as food is con- 
cerned Stichostemma is well supplied during the winter months. 
Apparently, then, the young of the preceding autumn reach 
their full size during the winter, reappearing near the surface 
with nearly ripe eggs as soon as the ice disappears. 
During the winter of 1900-1901 the lagoon was wholly cov- 
ered with six to eight inches of ice before the end of Decem- 
ber, and the temperature during the greater part of January 
and practically the whole of February was far below 32°. The 
ice became exceptionally thick and did not disappear till near 
the end of March. The worms were not found along the shore 
until April 12, and then only a few appeared, all of them large 
and filled with eggs which were about half grown. During 
the early part of December, 1900, before the lagoon was com- | 
pletely frozen over, the worms were more abundant than I had 
ever found them before. Their late appearance and small num- 
bers in April, 1901, must probably be attributed to the pro- 
tracted cold weather and the thickness of the ice in the lagoon. 
During the months of May and June comparatively few 
full-grown specimens are found, but the young are increas- 
ingly abundant as the season advances. These become sexual 
about July 1 or a little earlier. By this time nearly all the old 
worms which survived the winter have disappeared. During 
the remainder of the summer the worms continue to increase 
in numbers until freezing kills them or drives them to deeper 
water. 
There is no evidence that the worms possess the power of 
entering upon a resting stage of any kind which is capable of 
enduring freezing without injury, though there are some facts 
that indicate the possibility that they may become more or less 
quiescent for a short time. When the animal is brought under 
conditions which are disagreeable to it, or is irritated, it secretes 
a large amount of slime and in many cases becomes enclosed 
in a covering of slime, which gradually contracts and becomes 
more dense until it resembles a cyst. Within this the worm 
