696 RECORD OF CURRENT RESEARCHES RELATING TO 



Wicker sheimer's Preservative Fluid and Vegetable Objects.* — 

 Dr. K. Prantl describes the results of his cxperiraeuts with this 

 fluid,f which, though so valuable for animal substances, he judged 

 beforehand would not be applicable to parts of plants. The density 

 of the fluid removes the turgidity of the cells without harden- 

 ing the protoplasm quickly ; hence the delicate parts of the plant 

 lose their firmness, and consequently their relative jiosition, even 

 in the fluid. The flowers of Tropoiolum, for examjile, collapsed 

 after being a few hours in the fluid, and became unrecognizable. 

 The lamellae in the pileus of different Agnrici were greatly distorted, 

 not only after being taken out of the fluid, but whilst still in it. 

 Those parts of a plant which possess sufiicient consistency alone 

 preserve their shape, as Ferns rich in sclerenchyma {Blechnum 

 australe), and the leaves of Conifer^e, objects which can be preserved as 

 well dry. If pine branches, however, arc laid in the fluid, the falling 

 off of the acicular leaves in drying is prevented, but this can be done 

 just as well by concentrated glycerine. 



Further, the fluid kills the protoplasm, hence the colouring 

 matter held in solution by the cell-sap comes out in a short time. 

 Chlorophyll has hitherto been retained, but changed into a brownish 

 tint. 



Hardening Canada Balsam in Microscopic Preparations by Hot 

 Steam.l — The inconvenience arising from the slowness with whicli 

 Canada balsam hardens, especially in summer, has been felt by all 

 engaged in making permanent preparations. M. Passauer describes 

 a small and simple apparatus which he made for the purpose of over- 

 coming this objection. It consists of a round vessel of tin, about 

 18 cm. in diameter and 6 cm. deep, with a tin cover 19^ cm. square 

 (for convenience in placing the slides), to the under surface of which 

 a circular rim about 1^ cm. decji is sohlered and made to fit easily 

 into the vessel. On the upper side the cover is also furnished with a 

 rim about 5 mm. deep. In one corner of the lid, but inside the lower 

 circular rim, a tube 6 cm. in diameter and 10 cm. long is soldered 

 and passes through the lid. 



In using it the vessel is half filled with boiling water, covered 

 with the lid, and the prej^aration to be hardened laid on the latter, 

 and the temperature of the water kept at boiling-point by a lamp 

 placed under the vessel. Special care must be taken that the steam 

 does not become too hot, otherwise bubbles would be produced in the 

 balsam and the prejjuration be spoilt, hence the small chimney is 

 provided, through which part of the steam can escape. By this means 

 the balsam can be hardened in 1 to 1^ hours. 



Ringing and Finishing Slides.§— The following article by Dr. C. 

 Seller gives some useful hints : — " A gi'cat deal may be said in favour 

 of and against the careful finishing of microscopical slides, but nobody 

 will deny that a nicely-ringed preparation looks better in a cabinet, 



* ' Bot. Centralbl.,' i. (1880) p. 26. t Ante, p, 325. 



t ' Zeit.sclir. f. Mikr.,' ii. (1880) p. 194. 

 § ' Am. Jouin. Micr.,' v. (1880) p. 94. 



