212 [June, 



which had become black, occasioned by the actual deposit of pigmen- 

 tum nigrum in the rete mucosum. 



June \lth. 



Dr. Leidy read a continuation of his paper entitled *' Contributions 

 to Helminthology ;" which was referred to Drs. Bridges, Ruschenber- 

 ger and Fisher. 



Dr. Leidy stated that he had examined microscopically, the specimen 

 of nigrities which had been exhibited by Prof. Horner at the last meet- 

 ing ; and that it proved to be a true deposit of pigraentum nigrum in 

 rete mucosum. 



A letter was read from the Rec. Sec. of the Penna. State Med. Soc, 

 dated Philadelphia, June 10th, 1851, transmitting a resolution of thanks 

 from that Society for an invitation to visit the Museum of the 

 Academy. 



Dr. Leidy stated he had repeated the experiment of introducing cancerous mat- 

 ter beneath the integument of a frog, which was first announced to the Academy, 

 May 6th. 



The cancerous matter was a fragment of encephaloid, taken from a female after 

 death, by Dr. Henry H. Smith. It was almost as soft as cerebral substance. 

 Beneath the microscope it exhibited a structure of very delicate organic cells, 

 containing numerous granules and one of two nuclei. 



A portion Iths of an inch long, by ith of an inch broad, was inserted under the 

 skin of the back of a frog, on May 8th, 34 hours after its removal from the body 

 of the female. This frog, still living, Dr. L. exhibited to the members, and by 

 an incision through the integument, presented to view the fragment of cancer 

 which had been introduced, and which had not only formed a vascular attachment 

 to the integument, but for one half itself was of a fine red color from the net-work 

 of capillaries which had become developed within it. The fragment had not in- 

 creased in size. A number of its structural cells remained unchanged, but others 

 had broken down into granular masses. 



Dr. L. observed, the experiment not only proved the independent vitality of 

 tissues, which was generally admitted, but also rendered it exceedingly probable 

 that cancer was inoculable, for, as in the experiments, the cancerous fragments 

 continued to live when introduced into cold-blooded animals, they would probably 

 not only continue to live when introduced into warm-blooded animals, but would 

 grow or increase in size. 



Dr. Zantzinger announced to the Society the decease of William 

 Hembel, Esq., which occurred on the 12th inst., at his residence in this 

 city, at the advanced age of 88 years. His long connection with the 

 Institution, his liberality to it on many occasions, his position as its 

 President for nine years, and his scientific and literary acquirements, 

 eminently entitled him to honorable mention on the present occa- 

 sion. 



