381 



due to arrested development. Dr. Wyman's hypothesis is that a 

 primary single vesicle is formed on tlie median line, instead of 

 one on each side, as in the normal condition — this must remain a 

 disputed point until some one is enabled to examine this class of 

 monstrosities in their earliest stages. 



Dr. Bacon exhibited a series of first class microscopic 

 objectives, made by Mr. Grunow, of New Haven, Conn. ; 

 they embraced the most useful working powers, and in 

 them allowance was made for the thickness of the glass 

 covering the object. He explained the mechanism of 

 the adjustments, and alluded to their wide angular aper- 

 ture as of great importance, when not carried to excess, in 

 bringing out the finer details of microscopic structure. 

 Their power was tested on some very delicate photo- 

 graphs, diatoms, and other minute objects. 



Dr. Durkee stated that a house at the south part of the city, 

 occupied for several years by the same family, had been infested 

 for the past year by mosquitoes ; these pests were exceedingly 

 numerous in the cellar, kitchen, and basement, but less so in the 

 upper rooms, though the house was occupied by them from attic 

 to cellar. He was at a loss to account for this singular visitation, 

 as the cellar was dry, there was no cistern nor vessel of stand- 

 ing water on the premises, and other houses in the neighbor- 

 hood were not similarly troubled. The. family have been obliged 

 to use mosquito bars for protection all winter, with the exception 

 of about fifteen days in February. They were exceedingly an- 

 noying, invading even the sugar-bowl ; and so numerous in a jug 

 of molasses that there was taken out a large teacup full of them. 

 He exhibited a nest of mosquito eggs preserved in fir balsam. 



Mr. Stodder exhibited under the microscope a supposed 

 new diatom of the genus Tri/blionella, to which he gave 

 the specific name elliptica ; he obtained it from the Back 

 Bay, Boston, where it is very common ; he also showed 

 finely executed drawings of the same. 



On motion of Mr. J. M. Barnard, it was voted that 



