373 



largest. After they had swallowed them, they seemed very un- 

 easy, moving the bones of the head and jaws, and contorting 

 their bodies in various ways, as if they did not feel quite easy in 

 their stomachs ; however they at last became quiet, but at the 

 end of twenty hours they became uncommonly active, and the 

 three fish were regurgitated, with the scales off, the eyes out, 

 and the entrails of the smallest gone ; they were perfectly white, 

 and looked like ghosts of fish. It was either diet too gross for 

 their delicate and weakened stomachs, or else not sufficiently 

 comminuted for the action of their gastric juice. 



Mr. H. J. Clark, referring to the opinion expressed by 

 Prof. Agassiz at the last meeting, that those organs in 

 hydra which are considered to be testes, are in reality 

 clusters of superficial lasso cells, stated that he had de- 

 tected spermatozoa in motion in these bodies. Prof. A. 

 said that he now remembered having been informed 

 by Mr. Clark of this fact, and that therefore the idea 

 conveyed by him at the last meeting was incorrect. In 

 his remarks made at that time upon the lasso cells, he 

 desired to be understood that all which was original 

 with him was the direct evidence that the lasso thread is 

 hollow, and that it is everted in the process of throwing 

 out. 



Prof. Agassiz presented some observations upon Co- 

 rals. He had been led by his investigations to classify 

 corals under four different heads, belonging to four differ- 

 ent classes of organized beings, as follows : — 



1st. Vegetable Corals. These are Algaj, or at least vegetable 

 productions, which in time accumulate in their cellular tissue so 

 much lime as to resemble coral, and which form entire islands, 

 as the Tortugas and Marquesas groups, the sands on the shores 

 of which are composed of disintegrated particles of these vege- 

 table growths. 2d. Corals of Bryozoa. The affinities of these 

 are well known. They grow in clusters, and are genuine corals 

 belonging to animals of the class of mollusks, and not polyps, 

 though once thus considered, od and 4th. The remaining corals 

 belong to two types, genuine corals formed hy Polyps and those 



