104 



a question of considerable physioloo:ical interest, whether here there 

 was a single or two organisms. C. F. Wolff maintains that there may- 

 be two primitive stripes on one germinal membrane, or one bifurcat- 

 ing at the top or at the bottom, thus making double monsters single 

 organisms. 



Prof. Agassiz said that he thought that the study of corals would 

 show that the general idea of individuality is not correct. Astrcea 

 grows by single tubes, growing in length but not enlarging in diame- 

 ter, and the buds arise from the interstices between the tubes by the 

 vital power of individuals ; in other corals the buds grow from the 

 sides, and may form independent and disconnected individuals ; in 

 others the tubes become wider with the increase of length, and finally 

 form two tubes, with two mouths and two stomachs, and yet the two 

 branches have j^roceeded from a single organism; two individuals 

 have been developed from one base. 



Prof. Agassiz announced that Capt. Anderson had left with him, 

 for presentation to the Society, a pamphlet on the deep sea sound- 

 ings of Capt. McClintock in the surveys made in connection with 

 the North Atlantic telegraph, and also embracing Dr. Wallich's ob- 

 servations on living star-fishes taken from the great depth of 1260 

 fathoms ; from the details of the experiments he was satisfied that 

 these animals had lived at that depth. In order to withstand the 

 pressure to which these animals must be subjected, without being 

 crushed, he maintained that water must penetrate their tissues very 

 freely. The fluid penetrates in fishes through minute pores commu- 

 nicating with the venous sinuses near the heart ; these are to be seen 

 by the naked eye on the sides of the head of the herring and shad, 

 and enable these fishes to make the change from deep water in 

 the winter to shoal water in the spring, when they approach the 

 shore to spawn. In mollusks they are limited chiefly to the foot ; in 

 echinoderms they vary in different families, being sometimes in slits, 

 and at others admitting water into the aquiferous system through the 

 madreporic body. 



Considerable discussion followed as to the necessity of any 

 such arrangement for resisting pressure at great depths. 



A letter was read from Capt. Anderson, accepting corre- 

 sponding membership of the Society. 



Messrs. Horace Mann, of Concord, and Elbridge Gerry 

 Dudley, of Boston, were elected resident members. 



