NATURAL SCIENCES OF PHILADELPHIA. 9 



far as we desired. "We therefore hesitated to publish the results of our 

 examination of the chemical nature of these poisons, but upon more 

 mature reflection have concluded to lay them before the scientific world, 

 trusting at some future period to be enabled to present a more complete 

 memoir on the subject, and to correct any errors into which we may have 

 fallen in the course of the researches just concluded.* 



May. 



1. Physiology. 



A paper was read, entitled, " Food of the Shad of the Atlantic Coast 

 of the United States, (Alosa sapidissima,) and the functions of the 

 pyloric c&ca. By E. R. Mordecai, M. D., of Mobile, Alabama. 



This paper, after calling to mind the anatomy of the alimentary canal of 

 the shad, lays particular stress upon the facts that the teeth are very 

 small, and of such an arrangement as to suggest its food to be easy 

 of prehension ; that the largest, longest, and also the greatest number of 

 the caeca open into the inferior wall of the expansion of the intestine 

 that is found beyond the pylorus. 



On examining the intestines of a number of shad, fresh run from the 

 sea, the caeca were always found to be distended by a brownish-looking 

 fluid substance, not differing to the naked eye from a fluid material of the 

 same color, filling the stomach. This fluid under the microscope, both 

 that from the stomach and from the caeca, was seen to be composed of 

 differently shaped and colored fragments of algae and the calcareous shields 

 of infusoria. 



The food of the shad would therefore appear to be marine algae, which 

 are broken down by the powerful muscular walls of the stomach, aided 

 by the broken shells of infusoria. The caeca are receptacles for food ; 

 enabling the animal to exist for a considerable time without receiving 

 additional nourishment. 



Arguments in favor of these views are drawn by Dr. Mordecai from 

 an analogous condition of things in other fish, that ascend fresh water 

 streams, or seek other places than those likely to supply them with food, 

 for the purpose of spawning. 



Specimens mounted for microscopical examination accompanied this 

 paper ; and the statements above made in regard to the contents of the 

 stomach and the caeca, were abundantly verified by members of the 

 Academy. 



*Some misconception appears to have been occasioned by the names under which we 

 have studied these poisons. In our first essay they were distinguished as " corroval and 

 vao, two new varieties of woorara, the South American arrow poison." In consequence 

 of this title, it has been supposed that we regarded corroval and vao as identical with 

 the woorara of De-la-Condamine, Kolliker and others. No person, however, who went 

 beyond the tiile of the papers, could possibly entertain this idea, since the toxicological 

 distinction is drawn in ihe most definite manner. All the specimens of corroval and vao 

 which we have seen, have come to us labelled woorara, and we have been informed 

 that this term, or the more specific appellation, were indiscriminately used by the 

 Indians of the Rio Darien. 



I860.] 



