378 proceedings of the academy of [1885. 



September 29. 

 Mr. J. H. Redfield in the chair. 

 Twenty-five persons present. 



October 5. 



Mr. Geo. W. Tryon, Jr., in the chair. 



Twenty-four persons present. 



A paper entitled "Attack and Defence as Agents in Animal 

 Evolution," by Charles Morris, was presented for publication. 



October 13. 

 The President, Dr. Leidy, in the chair. 

 Thirty-four persons present. 



Notes on Gactaceee. — Elastic Fruit in Mamillaria. — At the 

 meeting of the Botanical Section of the Academy, held on the 

 12th inst., Mr. Meehan referred to his former observations on 

 the sudden growth of the fruit of some species of cactacese, indi- 

 cating that it was not a growth before maturity, but an elastic 

 projection of a fruit already mature. Since that time he had been 

 able to note in Mamillaria gladiata, M. recurva, and some other 

 Mexican species, in which there was only the apex of the red 

 fruit visible between the mamma over night, a full elongation to 

 the length of an inch by 9 A. M. the next day. They were clear 

 cases of the elongation of the fruit after maturity and not a 

 growth. 



The (lowers of Opuntia Rafinesqui had very irritable stamens 

 when the Mowers were fully expanded under a bright sun. Some 

 echinocacti had stamens irritable in a less degree, but in Echino- 

 cactus efinaceus the stamens were quite as irritable as in the 

 opuntia noted. 



On the Flora of Martha's Vineyard and Nantucket.^-At the 

 ~.niie meeting of the Botanical Section Mr. Redfield spoke of 

 the topographical features of Martha's Vineyard and Nantucket, 

 in connection with the flora of those islands. The northern por- 

 tion of the island of Martha's Vineyard rises into rounded 

 hills of considerable elevation, composed of gravelly drift, 

 strewn occasionally with large boulders. The}' are evidently 



