ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 637 



in the ordinary way, except with anilin ]>igments as these are extracted 

 by immersion in water. 



Having completed the stain ini,^ process, the section is put into water, 

 and is now witlioiit further treatment ready for mouiitin.a; in the gelatin 

 solution. 



In the preparation of this a few essentials must be noted. Firstly, 

 the solution must be freshly made and the best results are only obtained 

 when the special gelatin, as used for photographic plates, is employed. 

 Of this, 10 grm. are taken and allowed to soak for two hours (preferaljly 

 overnight) in 100 c.cm. of distilled water. When about to l)e used this 

 solution must be warmed to a temperature of 50' C. by means of a water 

 bath in order to render it sufficiently fluid. It is advisable to filter it 

 beforehand also at this temperature. 



As much of this warm solution is then gently poured on to the slide 

 as can be put on without any overflowing. It is important to pour on 

 as much as possible in order to get a sufficiently thick film of gelatin in 

 the final result. When large sections are being treated it is better to 

 keep the slide on a warm stage, and in the case of frozen or celloidin 

 sections to pour on a thin layer of the gelatin solution first before 

 putting the section in position on the slide. Larger sections still can, 

 with profit, be immersed in the solution for a few minutes beforehand. 

 The preparation is now left exposed to the air, and in the course of a 

 few hours the water evaporates and one is left with the sKde covered 

 with a fine transparent film of gelatin in which the section is embedded. 

 This film behaves in every particular like the gelatin film on a photo- 

 graphic plate. It is intensely hard, resists scratching, and can be 

 packed face to face with other specimens without involving the risk of 

 finding them glued firmly together as is the manner of Canadian balsam. 

 Under the Microscope a perfectly clear picture is given, and if necessary 

 cedar-wood oil, for oil immersion purposes, can be used. 



The great advantage of the method is the economy of time and 

 material which results. There is no tedious transferring from dish to 

 dish for the processes of dehydrating and clearing. Thus alcohol, xylol, 

 Canada balsam, and cover-slips are entirely dispensed with, and in 

 addition one does away with the danger of injuring large brain sections 

 which attends too much handling. Apparently specimens will keep 

 indefinitely. Weigert-Pal preparations — for . which the method is 

 eminently suitable— have been preserved for three years. Serial sec- 

 tions, which require large slides and cover-slips, lend themselves in this 

 manner of mounting. Finally, perhaps, botanists may find here a useful 

 servant. Their chlorophyll specimens, being untreated by alcohol, are 

 able to retain their pigment unaltered, and so can be mounted in the 

 natural state. 



(6) i. Miscellaneous. 



New Suction Cap.* — T. Kitt describes a type of rubber suction cap 

 for the purpose of drawing fluid into pipettes, which has advantages 

 over the common rubber teat. This consists of three parts, a lower 

 tubular section which fits over the end of the pipette, an intermediate 



* Centralbl. Bakt., Ite Abt. Orig., Ixx. (1913) p. 447. 



