1044 SUMMARY OF CURRENT RESEARCHES RELATING TO 



cover-glass. Tlio first complete section wliicli finds its way into the 

 white pan jtlaccd at a level of about one inch below that of the sections, 

 is removed on the cover-glass to a dish of distilled water, wherein it 

 remains for some hours. The sections are then stained with alum-car- 

 mine, picrocarminc, or ammonia-carmine. With picrocarmine rapid stain- 

 ing on the slide is best. In alum-carmine the section on the cover-glass 

 may be left all night. Then transfer to distilled water to remove alum 

 crystals. 



Some of the imstained sections may be cleared up by Hamilton's 

 liquor potasste method. Having been thoroughly washed, pour over 

 the sarfrtcc of the sections with a pipette a solution of liquor potassfB 

 1 : 4 water. To imbed and mount take a quantity of gelatin, w-ash and 

 cover with a saturated solution of salicylic acid. Soak all night, then 

 pour ofi" superfluous water and heat over a water-batli until the whole is 

 thoroughly melted. To every one part of this add two parts of glycerin. 

 Heat over water-bath, keeping it stirred until the whole is thoroughly 

 mixed, strain through a piece of close flannel into a flask in which it 

 may be reheated as required. Having allowed most of the water to 

 drain away, the slide is placed on a level stand, and a thin layer of warm 

 glycerin jelly run slowly and gently over the surface by means of a 

 pipette ; then set aside to cool. To finish off tho preparation, the slide 

 on which the section is to be mounted is placed on three or four pieces of 

 cork over a water-bath until it is warmed through. It is then transferred 

 to the tripod, and a quantity of jelly is passed on to the centre and 

 gradually on to the end nearer the manipulator. The cover-glass is 

 then gently lowered down, the near end fii'st. The jelly on the cover- 

 glass keeps the section in position long enough to allow of the cover- 

 glass coming into its place. The slide usually retains sufficient heat 

 to melt away all superfluous jelly. Should this not be the case, the 

 whole slide may be again heated and the extra mounting medium gently 

 squeezed out. If there be any surplus at the margin of the cover the 

 slide may be left for some time without further treatment. To preserve 

 the specimen, remove the extra jelly with a knife, wipe carefully first 

 with a moist, and afterwards with a dry cloth. Then paint round the 

 margin several layers of benzol balsam. This must be done at onco 

 after the superfluous jelly has been scraped away, otherwise air-bubbles 

 get in owing to the jelly becoming dry. It is convenient to mount these 

 slides in common wooden frames. 



Cleansing the Intestine of many animals of sand.* — Dr. Kukenthal 

 remarks that the grit present in the gut of many animals, and which is 

 due to their way of life, prevents the preparation of thin sections. 

 Such is the case with the earthworm. The author advises that the 

 animal be first washed clean and then be placed for some time in a tall 

 glass vessel which has been filled up with bits of moistened blotting- 

 paper. The worm gradually evacuates the earthy particles from the gut 

 and fills it instead with paper. 



Killing contractile Animals in a state of extension.t — M. L. 

 Eoule divides the contractile animals into those which contract 

 rapidly, like Actinife, Hydroids, Bryozoa, and Ascidians, and those 

 which contract more slowly, like Alcyonium and Veretillum. The latter 



* Tagebl. 60. Versamml. Deutscher Naturf. u. Aerzte : Wiesbaden, 1887, p. 259. 

 t Ai'ch. Zool. Expe'r. et Ge'n., vi. (1888) pp. v.-vii. 



