December 6, 1875. 

 Dr. S. Pollack in the chair. 



Nine members present. 



Mr. Riley, from Committee on Publication, laid sig. iS of the 

 Transactions upon the table. 



The Corresponding Secretary laid a number of exchanges on 

 the table, and read a communication from the Secretary of the 

 Soc. of Nat. Hist, of San Diego, Cal., making inquiries relating 

 to the effects of forests on rainfall, which letter was referred to 

 Dr. G. Engelmann for answer. 



JUMPING SEEDS AND GALLS. 



Mr. Riley exhibited certain seeds which possessed a hidden power of 

 jumping and moving about on the table. He stated that he had recently 

 received them from Mr. G. W. Barnes, of San Diego, Cal., and that they 

 were generally known by the name of "Mexican Jumping Seeds." They are 

 probably derived from a tricoccous euphorbiaceous plant. Each of the 

 seeds measures about one-third of an inch, and have two flat sides, 

 meeting at an obtuse angle, and a third broader, convex side, with a me- 

 dial carina. If cut open, each is found to contain a single fat, whitish 

 worm, which has eaten all the contents of the seed and lined the shell with 

 a delicate carpet of silk. The worm very closely resembles the common 

 Apple Worm (Carpocapsa potnonella), and, indeed, is very closely rela- 

 ted, the insect being known to science as Carpocapsa saltitans. It was 

 first recorded by Westwood in the Proceedings of the Ashmolean Society of 

 Oxford, in 1857 (t. 3, pp. 137-S), and repeatedly referred to under the name 

 of Carpocapsa Dekaisiatia in the Annales of the French Entomological 

 Society for 1859. The egg of the moth is doubtless laid on the young pod 

 which contains the three angular seeds, and the worm gnaws into the suc- 

 culent seed, which, in after growth, closes up the minute hole of entrance, 

 just as in the case of the common Pea Weevil (Bruc/itts pisi"). Toward 

 the month of February the larva eats a circular hole through the hard 

 shell of its habitation, and then closes it again with a little plug of silk so 

 admirably adjusted that the future moth, which will have no jaws to cut 

 with, may escape from its prison. A slight cocoon is then spun within 

 the seed, with a passage way leading to the circular door; and the hitherto 

 restless larva assumes the quiescent pupa state. Shortly afterwards the 

 pupa works to the door, pushes it open, and the little moth escapes. 

 When ripe, the shell is very light, and, as the worm occupies but about 

 one-sixth the enclosed space, the slightest motion will cause the seed to 

 rock from one of the flat sides to the other. But the seed is often made to 

 jerk and jump, and, though this has been denied by many authors, Mr. 

 Riley had had abundant proof of the fact, and had seen the seed jerked 

 several lines forward at a bound, and raised a line or more from the 



