No. 420.] HISTORY OF STICHOSTEMMA. 995 
cyprids actually attacked the active, healthy specimens. Occa- 
sionally they crawl over the body, but very soon leave it again, 
apparently without inflicting injury. In a series of experi- 
ments in which two or three specimens of Stichostemma were 
placed in small jars of clear water with hundreds of cyprids, it 
was found that although the worms remained alive and appar- 
ently uninjured for a day or two, they were finally completely 
devoured. When specimens of Stichostemma were cut in 
pieces and thrown into a jar containing numerous cyprids, 
they were rapidly devoured. In other experiments two or 
three worms were placed in a small dish with several dragon- 
fly nymphs, which were given no other food. The nymphs 
occasionally attacked the worms, sometimes biting them in 
two. Within two days the worms were usually bitten into 
several pieces or killed, but not devoured. At the conclusion 
of the experiments the same nymphs took Gammarus eagerly, 
thus showing certainly that they were not satiated with food. 
Their attacks upon Stichostemma were often observed. The 
worms were picked up and held by the large labium for a 
moment, sometimes bitten completely through and allowed to 
drop almost immediately, or occasionally bitten at various points 
and badly crushed, but not eaten so far as could be observed. 
The worms frequently crawled over the surface of the nymphs 
without exciting any response from the latter. It is of course 
possible that the nymphs devour small portions, but they are 
certainly not sufficient to satisfy the hunger of these voracious 
feeders. . 
The worms are unable to escape from predatory forms by 
rapid movements, for their movements are all relatively slow. 
It was very evident during the experiments that the nymphs 
often saw the worms when at some little distance from them 
and approached them, perhaps reaching out and grasping them 
for a moment only to let them drop again. In such cases the 
nymphs had not the slightest difficulty in approaching the 
worms. 
It would appear that Stichostemma, especially when filled 
with eggs, would afford an inviting morsel for many predatory 
aquatic forms, and that without some means of protection its 
