NATURAL SCIENCES OF PHILADELPHIA. 415 



December 9. 

 Mr. Vaux, Vice-President, in the chair. 

 Twenty-eight members present. 



On the Expansion of the Coma in Asclepiadacese. Mr. Thomas 

 Meehan exliibited some seed-vessels of Gonolobus obliquus, and re- 

 marked, that, though the hairy appendage to the seed known as the 

 Coma in aselepiaclaceous plants was of course well understood, 

 he knew of no one who had placed on record any observation in 

 regard to the suddenness of the expansion after the seed left the 

 capsule. It was indeed so very rapid, that the common expres- 

 sion of "like a stroke of lightning," was scarcely an exaggeration. 

 It was only with difficulty that the eye could follow the motion. 

 In the seed-vessel each set of long silky hair was drawn up into a 

 close linear fascicle ; but on the instant of the seed being relieved 

 from its case, the coma expanded into a perfect hemisphere. 

 Some of the hair formed a right angle, and others more or less 

 acute ones, each seeming to have its fixed place to fall back to. 



It was generally supposed that these hairy appendages and 

 others of a similar character in seeds, were for the express purpose 

 of aiding in seed distribution by wind ; but he had failed in so 

 many instances to see the advantages, that it often seemed as 

 if it were the seed profiting by developed organs, rather than 

 that these were especially formed for an express purpose. 

 The wings of the linden and maple, for instance, give a peculiar 

 spiral motion to the descent of the seed, without any apparent 

 benefit to the seed from the spiral motion ; while the wing, espe- 

 cially in the case of the linden, did not carry the seed far away. 

 But in this case of the Gonolobus, it did seem as if there were 

 better grounds than perhaps in any other case for believing that 

 the hairy appendage is designed expressly to facilitate distribution 

 by wind or air currents. The seeds are heavy, and are borne on 

 the plant but a few feet from the ground: they would fall there 

 in a few seconds on the opening of the capsule, if the mass of 

 hair remained long in its closely compact condition. It was indeed 

 absolutely essential, to be of any use at all as an aid to the wind, 

 the expansion should be immensely rapid. He thought it the most 

 perfect illustration of express design he knew in the vegetable 

 kingdom. 



On Lingula in a, Fish of the Susquehanna. Prof. Leidy re- 

 marked that Dr. Chapman had submitted to his examination 

 several entozoa, together with portions of the stomach and intes- 

 tine, of a 3'ellow Pike-perch, Schizostedion, or Lucioperca ameri- 



