168 PROCEEDINGS OF THE AMERICAN ACADEMY 



It was Diitrochet's theory, that this action is due to the sudden 

 transfer of fluid from the inner to the outer cells of the wall of 

 the capsule. Dr. Wyman had demonstrated the impossibility 

 of this, by dissecting away the outer layers of cells without im- 

 pairing at all the contractility of the capsule. He had himself 

 come to the conclusion, that the motion is due to the spontane- 

 ous contraction of the cells on the contracting side, in the way 

 that motion is produced in the hydroid polyps. In the con- 

 tracted capsule the cells on the concave side are found to 

 be shortened, while those on the opposite side are elongated. 

 In the Balsam capsule the contraction is so sudden that the 

 shortening of the cells cannot be watched, but in the Echi- 

 nocystis the motion is so gradual that the change can be ob- 

 served under the microscope. When gradually subjected to 

 the action of anassthetic agents, the capsules lose their con- 

 tractility ; but when suddenly placed under their influence, an 

 immediate contraction is the usual result. 



Four liundred and seveutli meeting. 



December 12, 1854. — Quarterly Meeting. 



The President in the chair. 



Dr. Durkee read a paper on the Common Mosquito, Culex 

 pipiens, giving a description of the microscopic structure of 

 its proboscis, with an account of its development and habits of 

 reproduction. 



On motion of the Treasurer, the following vote was 

 passed : — 



" Whereas, the American Academy of Arts and Sciences has re- 

 ceived notice from the executors of the will of the late Samuel Apple- 

 ton, that they have transferred to this society stocks amounting to 

 ten thousand dollars, from the fund left for distribution by Mr. Ap- 

 pleton, — 



" Voted, That the Academy accepts with much gratification this 

 contribution to the cause of Science from one who found his happiness 

 in acts of beneficence, and that our thanks are due to the executors of 

 his will for the direction which they have given to his bounty." 



