128 MANTON COPELAND. 



locomotion, and if so, when the animal came to rest, did ciliary 

 movement stop, or did it continue without effecting forward 

 movement? That the cilia did not beat continuously was soon 

 demonstrated. A support for the snail was made by fastening 

 with "sticky-wax" a short glass tube to the bottom of a glass 

 dish containing sea water. The snail's shell was then stuck up- 

 side down to the end of the pedestal so that the ventral surface 

 of the foot when fully expanded was at the level of the water. 

 In this position the animal usually exhibited righting move- 

 ments for a time, but soon spread out its foot on the surface 

 film of the water. Often the flicker of the cilia could be seen 

 with the naked eye and readily observed under a hand lens. 

 Grains of carmine w T ere swept down the foot by ciliary activity. 

 At other times, however, the cilia were quiescent and carmine 

 grains remained on the foot where they were dropped. When a 

 snail resting in this position was stimulated by touching one of 

 its tentacles with a piece of fish meat, the proboscis was protruded 

 and the cilia began beating. The proboscis was often worked 

 over the surface of the foot and at that time the ciliary move- 

 ment was greatly reduced or stopped. Usually after the pro- 

 boscis was withdrawn the cilia showed vigorous activity, the 

 foot was stretched out its full length, and the animal appeared 

 as it did when moving upside down on the surface film of the 

 water, a form of progression often exhibited when free in the 

 aquarium. In the later situation its behavior was essentially 

 like that when fixed in the position just described. As it moved 

 along the surface of the water the cilia could be seen in motion and 

 carmine grains were swept with the mucus down the foot. Fre- 

 quently the proboscis was extended and moved about in various 

 directions, and at this time ciliary activity and locomotion 

 ceased. 



By placing the dish, in which an inverted snail was fastened, 

 on the stage of a microscope, and by using a low power objective 

 the fringe of long cilia projecting from the anterior border of 

 the foot could be clearly observed. In one instance when the 

 animal was becoming quiet after feeding, the cilia could be seen 

 beating slowly near the tip of one of the anterior lateral foot 

 processes, whereas other cilia nearer the median position were 



