10 



succeeded in tracing them so far as to be able to distinguish 

 between vertebrata and invertebrata in the earliest stages of 

 development of the egg. 



The President remarked that every new instance of ovarian 

 impregnation was of great importance. The most recent re- 

 searches go to prove that the seminal fluid comes in direct con- 

 tact with the ovum, and perhaps enters into its substance ; but 

 in Anableps, the ovum is surrounded by a membrane which would 

 tend to prevent any such entrance. 



Prof. Agassiz observed that he considered fecundation as a 

 series of acts rather than a single act. In Chelonians, the cir- 

 cumstances under which the eggs are developed, would lead to 

 the inference that an impulse is first received from the male, and 

 then that four successive copulations in four successive years, 

 twice a year, are necessary before segmentation takes place in 

 the egg. In the Haddock, ovarian gestation has this physiologi- 

 cal import, that it shows that what is a normal condition in one 

 animal of a certain type, may be abnormal, and occur only ex- 

 ceptionally in another animal of the same type, as in man and 

 other of the higher forms of vertebrata. 



Dr. Gould inquired how ovarian impregnation took place in 

 fishes. 



Prof. Agassiz replied that he had seen certain fishes place 

 themselves in such a position that there was close approxima- 

 tion of the abdomens of each, whilst in the female the entrance 

 to the ovary was open to a very considerable extent. 



Mr. Bouv^, in behalf of the Committee appointed to 

 consider the subject of summer excursions, reported in 

 favor of the project, and proposed that the first excur- 

 sion should be made to Hingham and the neighboring 

 country. It was voted to assemble on board the Hing- 

 ham steamboat at 9 o'clock, A. M., on Wednesday, July 

 23, and it was understood that the Committee would 

 make arrangements for proper conveyances at Hingham 

 when the company should arrive. 



Dr. C. T. Jackson read an extract from a letter of Mr. 

 Roswell Field, of Greenfield, Mass., in which he says 



