550 S. Morgulis 



The worms were found along theedges of ponds between decaying 

 leaves. In aquaria they can be seen on the bottom with their tails 

 deeply embedded in the mud, and with the anterior parts of the 

 body extending out like poles, always at an acute angle with the 

 level of the bottom. When the water is disturbed, or when they 

 are approached by a pipette, they instantaneously disappear under 

 the mud. 



To mechanical stimuli, such as irritation by means of a sharply 

 or bluntly pointed object, Lumbriculus responds more or less 

 readily: the more anteriorly the stimulus is applied the more 

 rapidly and vigorously the worm reacts. No reaction, or only a 

 very slight one, is apparent when the tail is touched. If the ante- 

 rior end is stimulated by a current of water or by repeated tickling 

 with a needle, the worm remains quiet and motionless for a while. 

 This quietness may be easily misinterpreted as a failure to per- 

 ceive the stimulus, but such a conclusion would be erroneous. 

 Prof. C. O. Whitman gives a very interesting account of a similar, 

 but very much more striking kind of reaction in Clepsine.- He 

 points out that if the surface of the water is touched with the point 

 of a needle just above the animal's back, it ceases to respire and 

 becomes quiet, aptly called by Prof. C. O. Whitman — deceptive 

 quiet. That the animal, although motionless, is in a state of 

 active resistance, is shown by the rigidness of the musculature and 

 some other symptoms. In the case of Lumbriculus I could not 

 actually see the strained condition of the musculature, but the 

 stretching out of the setae is probably an indication of such a con- 

 dition. 



Clepsine in the condition of "active resistance" adheres to the 

 dish so firmly that it is very difficult to force its hold. "With one 

 end detached, the other will often hold against a pull strong enough 

 to snap the body in two." I have observed similar cases in Lum- 

 briculus. When stimulated, the worm sometimes becomes so 

 firmly attached to the surface of the leaf, that it is impossible to 

 draw it into the pipette, although a part of its body may be broken off 

 by the forcible current of water in and out of the pipette. This, 



'Prof. C. O. Whitman: Animal Behavior. Biol. Lectures. 



