NATURAL SCIENCES OF PHILADELPHIA. 205 



March 4. \lu i , 



Mr. Yaux, Vice-President, in the chair. \-^. 

 Twenty-six members present. 



Mr. Thomas Meehan exhibited a flower of Bletia Tankervillia 

 {Phaius grandijiora of some authors), in which the dorsal sepal 

 (or, as some authors contend, petal), had united with tlie column, 

 and had been much retarded in its development accordingly. 

 He said that he had several dozen of flowers produced in this 

 way this winter, all however confined to separate spikes from 

 those whicli V)ore tlie perfect flowers. In some cases flowers were 

 produced which had two of the exterior petals united together 

 perfectly, in which case the3'^ formed a hood over the apex of the 

 column. As changes of a similar character were not uncommon 

 in Orchidaceous plants, it was likely this form of changed struc- 

 ture had been seen before, though not falling within his own 

 observation. It was usual to pass over these appearances as 

 " monstrosities," but in truth the whole Orchid structure was 

 little less than a monstrosity. If we except the character of the 

 position of the seeds in the capsule, there was little to divide an 

 Orchid from an Iris, be^^oud the power of combining organs 

 which are free in the Iris the power which produced the " mon- 

 strosity" we see. The stamens were entirely coherent with the 

 pistil in Orchidaceous plants, and free in the Iridaceous. He 

 had seen in a " monstrous" Habenaria the lip so transformed, 

 that the whole flower had as regular an appearance as a Sisyrin- 

 chium in the Iridacese. 



He did not think as much had been made out of the changes 

 of structure in Orchids in the study of evolution, as miglit be, 

 in consequence of the impression that these abnormal forms, 

 as they were termed, were monstrosities, or the results of culti- 

 vation. There had been already on record accounts of changes 

 in wild Orchids more remarkable than many much dwelt on by 

 many modern writers on development. Sir Richard Schomburg 

 described and figured forty years ago, in the Linntean Transactions 

 (15tli vol.), three distinct genera Catasetum, Machranthus, and 

 Myanthus all growing out of one plant in Demerara ; and seed 

 which he took from one of these, and scattered on a piece of 

 rotten wood, produced plants with flowers of one of the otlier 

 genera. All these facts showed that the power of cohesion of one 

 organ witli another was one of tlie leading forces at work in 

 forming the Orchidaceous structure; and, as we saw in the speci- 

 men exhibited to-night, tliis power could be readily obstructed, 

 so as to produce many variations, it could hardl}' be said that 

 genera were founded on any absolute law. 



