ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 545 



ether, answers admirably. The coated slides may be kept indefinitely 

 before using. 



Paraffin sections are arranged upon the slide and a small amount 

 of a mixture of equal parts of alcohol and ether is then dropped upon 

 the slide. The liquid will be immediately drawn under the sections. 

 Bubbles of air will rarely remain beneath the sections, but, if they 

 do, they may easily be displaced by gently touching the section with 

 a soft brush. The liquid is allowed to evaporate spontaneously. 

 When quite dry, which will take but a few minutes, the paraffin may 

 be dissolved and the sections will be found firmly fixed. 



Celloidin sections are placed for a few minutes in 95 per cent, 

 alcohol, and then arranged on the coated slide. They are drained as 

 free of alcohol as possible, and as soon as their surface is nearly dry, 

 as is shown by its assuming a dull appearance, the mixture of alcohol 

 and ether is dropped upon them rather freely. When this has 

 evaporated until the surface of the sections again assumes a dull 

 appearance, the slide is placed in 80 per cent, or weaker alcohol, and 

 may then be treated by any of the reagents applicable to paraffin 

 sections fixed with collodion. 



The advantages claimed for this method are three : the use of heat 

 is dispensed with, and thus one source of inconvenience and injury 

 to the sections is avoided ; the paraffin is not removed (or melted) 

 until the sections are fixed, and thus in sections consisting of discon- 

 nected parts, the position of these parts is preserved ; labour and 

 work-table space are saved by having a single method, which is 

 applicable to both paraffin and celloidin sections. 



Peirce Cell for Opaques.* — This form of cell was devised by 

 Prof. J. Peirce, for " di-y mounts " (figs. Ill and 112). The cell and cap 

 are made from sheet brass, the latter fitting not too tight nor too loose. 

 While dust is perfectly excluded, the 



cover-glass and its frequent accom- Fig. 111. Fig. 112. 



paniment of "dewed" under surface 

 is done away with. " This gives the 

 additional advantage that the light by 

 which the object is seen does not have to pass twice through a cover- 

 glass, and thus the object is seen in its full clearness and beauty." 

 Prof. Peirce also recommends the use of these cells soldered to a 

 3 X 1 tin slide. 



A. — Mounting Odontophores of Snails. 



[Best mounted in a weak form of Goadby's solution.] 



Scientific Enquirer, I. (1886) p. 68. 

 Apel, W. — Beitrag znr Anatomie und Histologic des Priapulus caudatus {^am.) 

 und des Halicryptus spinulosus (v. Sieb.). 



[Method of killing Gephyrea. Amer. Natural., XX., 1886, p. 315 ; supra, 

 p. 532.] 



Zcitschr. f. Wiss. Mikr.,, XLII. (1885), pp. 459-529 (3 pis.). 

 See this Journal, ante, p. 73. 

 B.Sc. — Double-staining Botanical Preparations. [^PostJ] 



Scientif. Enquirer, I. (1886) p. 33. 



* Micr. Bull, (Queeu's), iii. (1S86) p. 3. 



