202 



In two or three hours it will be dry, and the second side may be ground in 

 oil. A file may be used at first, but must not be persevered in, and the operation 

 must be completed on the bare hone. When the second side shall have been 

 wiped wdth chloroform, it may be polished with a bit of silk upon the finger. 

 After spontaneous separation from the slide and paper in warm water, the 

 specimen should be well washed on both sides in cold water and then allowed to 

 dry. After immersion in chloroform for a moment, and having been examined 

 to ascertain if free from possibly adherent particles, the section is ready for 

 mounting. 



A few precautions are necessary with particular sections . Transverse sections 

 especially, should be dried between glass, to avoid warping, and very porous 

 structures should be well saturated vsdth glue and dried before being cut. 



In mounting, spread a suffi?ient quantity of old and thick Canada balsam upon 

 a slide, and when cold •p^a.ce the section upon it. Cover it now with a quantity 

 of equally inspissated balsam, warmed until it flows, and then immediately 

 warm the slide, being careful to employ the least possible heat. Depress the 

 section, and withdraw every air bubble towards the edge of the slide, vdth a 

 stout needle, set in a handle ; put on the cover glass slightly warmed, not flat, 

 but allowing one edge to touch the balsam first, press out superfluous balsam, 

 and the specimen is safe. The slide, when cooled, may be cleaned with a warm 

 knife, spirits of vsine and ammonia. 



The author of the paper expresses his conviction that neither Canada balsam 

 nor gum mastic will retain the first ground side of a specimen long enough 

 upon the slide to enable the preparer to reduce it to the requisite thinness, and 

 with both these substances heat must be employed, which is objectionable, 

 because most objects are thereby warped and cracked, and furthermore the 

 paper guard is indispensable for limiting and equalising the thinness of a 

 section. 



The writer has tried this method with very considerable success. — Ed. 



Marine Dredging. 



A week or two since, five or six members of theQ.M.C. were invited by 

 Mr. Marshall Hall to visit him on board his yacht, "The Norma," for the 

 purpose of obtaining a day or two's dredging at the mouth of the Thames. 

 The party joined at Southend, off the pier of which town the yacht was found 

 at anchor. The hospitable owner had already a new dredge on board, and 

 another one, which was not new, was taken down by one of the visitors. The 

 first attempt made with the new dredge proved a failure, as did every tria^ 

 made with it during the day. The old one was then hove overboard, and 

 soon yielded a large number of specimens. As the trial was merely considered 

 an experimental one, no note of species was made, but several were preserved 

 alive for some days, and exhibited at the next meeting of the Club, aad also 

 at the College of Physicians ; and we have, at the moment of writing, several 

 living specimens of Noctiluca miUaris, which were obtained on the second day 

 by means of a muslin net. 



Our chief object in recording the excursion, is to point out the rich harvest 

 of beautiful living organisms, which can be obtained at a comparatively small 

 cof^t by means of the dredge. Many, or indeed, most of the specimens obtained, 

 have only been seen ali\ e by professional naturalists, and but little is known of 

 their life history. Facts are required, and these facts can only be obtained by 

 the observations of a number of persons interested in the pursuit. It may 



