1884.] NATURAL SCIENCES OF PHILADELPHIA. 49 



The contraction and expansion occur at exact intervals, 

 together occupying the space of two seconds. It is in this way 

 that the blood is purified and its circulation controlled. These 

 observations were made with a sfeven-eighths inch objective. 



To ascertain how long the cilia upon the tentacles would con- 

 tinue their motion after separation from the body of the worm, 

 both lophophores of an adult were put off above their junction. 



At first the tentacles remained closed from the shock, but 

 soon they were expanded, the cilia displaying active motion, 

 and presently the two separated lophophores began to move 

 about in the zoophyte-trough. This motion was produced by 

 the action of the tentacles, which bent in all directions, the tips 

 touching the glass, and was not a result of the currents produced 

 by the cilia. In a few minutes one lophophore had crawled in 

 this manner quite across the trough, while the other remained 

 floating in the water near its first position. In the case of this 

 latter the motion was produced by the ciliary currents, and was 

 entirely distinct from the crawling above noted. 



During this time the decapitated worm had sunk to the bottom, 

 and, though turning and twisting a good deal, did not attempt to 

 protrude the mutilated support of the lophophores. Its body 

 was so much contracted that the segments were not above one- 

 third their usual size. 



At the end of five hours the worm was apparentlj^ dead, num- 

 bers of infusoria had collected to prey upon it, and the surface 

 of the body presented a roughened appearance as though covered 

 with tubercles. The lophophores were still crawling and swim- 

 ming about. 



At the end of the eighth hour the lophophores had ceased to crawl, 

 but the ciliary action, though feeble and uncertain, still continued. 

 The body of the worm was then covered with a thick fungoid 

 growth, consisting of transparent rod-like filaments three-six- 

 teenths of an inch in length ; some of the filaments presented a 

 beaded appearance. All motion of the cilia upon the tentacles 

 had ceased, and these also were being devoured by infusoria. 



The above experiment shows that the motion of the cilia con- 

 tinued about twice as long as the mutilated worm gave evidence 

 of life. 



Several individuals of Mana,yunkia were observed to be preyed 

 upon, while still living, by large monads, embedded in one or more 

 of the segments, which were sometimes excavated to a consider- 

 able degree. 



