or ARTS AND SCIENCES. 201 



fifteen minutes before. The number of ultimate cellules in a moving 

 string varied from two to fifty ; tbe greatest number of strings were 

 composed of only three or four, often six to eight, and rarely as high 

 as fifty. Very rarely the fibres split longitudinally, and in such in- 

 stances the fibrillie were most frequently long, and moved about with 

 undulations rather than a wriggling motion. A single ultimate cellule, 

 when set loose, danced about in a zigzag manner ; but whenever two 

 were combined, the motion had a definite direction, which corresponded 

 to the longer diameter of the duplicate combination ; and if only three 

 were combined, the spiral motion was the result of their united action. 

 What it is that causes these cellules to move, I do not profess to know, 

 but certainly it is not because they possess life as independent beings. 

 This much is settled, however, that we may have presented to us all 

 the phenomena of life, as exhibited by the activity of the lowest forms 

 of animals and plants, by the ultimate cellules of the decomposed 

 and fetid striated muscle of a Sagitta. I do not pretend to say that 

 everything that comes under the name of Vibrio or Spirillum is a de- 

 composed muscle or other tissue, although I believe such will turn out to 

 be the fact ; but this much I will vouch for, and will call on Professor 

 Agassiz to witness, that what would be declared, by competent au- 

 thority, to be a living being, and accounted a certain species of Vibrio, 

 is nothing but absolutely dead muscle." 



Professor Agassiz corroborated Mr. Clark's statements most 

 fully, and spoke of the discovery as one of the very greatest 

 interest and importance. 



Dr. A. A. Gould, in reference to the discussion on the dis- 

 tributipn of plants and animals, made some statements, illus- 

 trating the power of external agencies, with reference to the 

 shells of Japan. Out of nearly nine hundred shells from 

 these islands which he had examined, only seventeen had 

 been found both on the island of Niphon and on Jesso, 

 which are separated by a passage of only some forty miles 

 in width. The fact is accounted for by the existence of a 

 strong marine current from the north and west, which passes 

 through the strait. 



Dr. Asa Gray communicated two papers, as follows : — 



I. Characters of Ancistrophora, a new Genus of the Order 



VOL. IV. 26 



