NATURAL SCIENCES OF PHILADELPHIA. 143 



probably sufficient to distinguish the animal generically from 

 Amoeba, and in this view the animal ma}^ be named Deinamoeha 

 mirabilis. 



On the Mode in lohich Amoeba stoallows its Food. Prof. Leidy 

 remarked that he had supposed that Amoeba swallows food by 

 this becoming adherent to the body, and then enveloped much 

 as insects become caught and involved in syrup or other viscid 

 substances. He had repeatedly observed a large Amoeba, which 

 he supposes to be A. princeps^ creep into the interstices of a 

 mass of mud and appear on the other side without a particle ad- 

 herent. On one occasion he had accidentally noticed an Amoeba, 

 with an active flagellate infusorium, a Urocentrum, included be- 

 tween two of its finger-like pseudopods. It so happened that the 

 ends of these were in contact with a confervous filament, and 

 the glasses above and below, between which the Amoeba was ex- 

 amined, effectually prevented the Urocentrum from escaping. The 

 condition of imprisonment of the latter was so peculiar that he 

 was led to watch it. The ends of the two pseudopods of the 

 Amoeba gradually approached, came into contact, and then actually 

 became fused, a thing which he had never before observed with 

 the pseudopods of an Amoeba. The Urocentrum continued to move 

 actively back and forth, endeavoring to escape. At the next moment 

 a delicate film of the ectosarc proceeded from the body of the 

 Amoeba, above and below, and gradually extended outwardly so 

 as to convert the circle of the pseudopods into a complete sac, 

 inclosino- the Urocentrum. Another of these creatures was noticed 

 within the Amoeba which appeared to have been inclosed in the 

 same manner. 



This observation would make it appear that the food of the 

 Amoeba ordinarily does not simply adhere to the body, and then 

 sink into its siibstance, but rather, after becoming adherent or 

 covered by the pseudopods or bodj', is then inclosed by the active 

 extension of a film of ectosarc around it. 



The death of Dr. Jeffreys Wyman was announced. 



September 15. 

 The President, Dr. Ruschenberger, in the chair. 

 Twentj'-three members present. 



On the Motive Poioer of Diatomes. Prof. Leidy made some re- 

 marks on the moving power of diatomes, desmids, and other alga. 

 While the cause of motion remains unknown, some of the uses are 

 obvious. The power is considerable, and enables these minute 

 organisms when mingled with mud readily to extricate themselves 



