NATURAL SCIENCES OF PHILADELPHIA. 15 



After section of the pneumogastrics, the same effects follow the administra- 

 tion of viridia, showing that it is a direct depressor, either to the muscular 

 structure of the heart itself or to the ganglia contained in it. No effect follows 

 the introduction of viridia into the muscles of the thigh of the snapping turtle, 

 while a very small quantity introduced into the muscular structure of the 

 heart of the same creature acted promptly, showing the action to be a local 

 one. 



Veratroidia produces death in the same way, but there is no trembling ; while it 

 always vomits and sometimes purges. The action of the heart is at first marked- 

 ly depressed, but this is followed bj' a rebound, the pulsations increasing in force 

 and frequency. Dr. Wood considers this rebound due to an accumulation of 

 carbonic acid in the structure of the heart, temporarily overcoming the de- 

 pressing effect of veratroidia. When the pneumogastrics are cut, the usual 

 depression of the heart's action takes place ; but the Doctor has made but a 

 single experiment, and with regard to the rebound this was unsatisfactory. 



Nov. 2(7, 1869. 

 Director, S. W. Mitchell, M.D., in the Chair. 



Fifteen members present. 



Dr. S. W. Mitchell read a paper " On the Effects of the Admin- 

 istration of Opium and its Alkaloids to Birds." See Am. J. Med. 

 Hci. Jan., 1870. 



Nov. 15th, 1869. 

 Director, S. W. Mitchell, M.D., in the Chair. 



Seventeen members present. 



Five microscopic slides were donated to the cabinet by Mr. W. 

 H. Walmsley. 



Dr. Jos. G. Richardson exhibited a living specimen of menobran- 

 chus. He referred to the large size of its blood corpuscles, and, as 

 a result of their study, arrives at a conclusion at variance with that 

 of Dr. Beale, as to the existence of a distinct cell wall about the 

 corpuscle, since he believes that he has even seen the cell wall about 

 the crystal resulting from a single globule of the hsemoto-crystallin. 



Dr. Wood also stated to the Society that, whilst making his researches upon 

 the alkaloids veratroidia and veratria, he had occasion to administer these 

 alkaloids after section of the par vagum, and had been astonished to find that 

 they never purged or vomited when the pneumogastrics had been cut. At first 

 he had ascribed this to idiosyncrasies in the animals operated upon, but as 

 experiment after experiment afforded the same results, it became evident that 

 it was impossible to explain by individual peculiarities that which always 

 happened. The doctor had extended these experiments, using as purgatives 

 gamboge, calomel, podophyllin, extract of jalap and croton oil, and in all cases 

 he had been unable to purge after section of the pneumogastrics. 



Dr. Wood also exhibited colored drawings and mounted slides of 

 a variety of desmids, and made the following remarks ; 



The slides were prepared from a collection made by Dr. F. W. Lewis in Saco 

 Pond, a small lake of spring water in the White Mountains, not far from the 

 Crawford House. 



This very rich collection embraced the following new and old species : 



