ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 307 



Usually it appears advisable to stain the specimens in toto before 

 imbedding in paraffin and chloroform, and for this purpose 

 Grenacher's alum-carmine and borax-carmine are very highly to be 

 recommended. The long-known ammonium-carmine is also occasionally 

 useful. 



Dr. M, Schulgin,* in order to obviate the inconvenience that the 

 same portion of the knife has always to be used, has had a knife of a 

 somewhat different construction made (but which he does not esplain). 

 The advantage of this is that it can be moved along its whole length, 

 so that different portions can be used for cutting. 



Professor E. Kossmann writes,| "Many to whom the turning back 

 of the micrometer-screw of the microtome is an annoying delay, will 

 be thankful to me for pointing out to them that in two or three seconds 

 it can be turned back its whole length by using a kind of fiddlebow, 

 such as is used for drilling holes. The loop of the bow-string (made 

 of strong silk cord, waxed or rosined) is passed round the smooth 

 neck of the screw, and the bow is moved alternately to the left with 

 stretched, and to the right with slackened cord." 



Fixing Sections.! — Dr. J. Frenzel considers that the method of 

 Giesbrecht for fixing the preparation with shellac upon the slide has 

 the disadvantage of preventing the colouring of the sections, so that 

 the entire object must be coloured. To obviate this often serious 

 drawback, he employs the following method : — Dissolve guttapercha 

 in chloroform and benzine, and filter the solution when it has settled 

 until it is clear and almost colourless. With this solution, which 

 must not be too thin, and must only spread slowly over the glass, 

 smear the middle of a carefully-cleaned slide, and after it is dry, lay 

 the section on it. (1) If the preparations have been imbedded in 

 parafiin or a mixture of paraffin (e. g. four parts of paraffin and 

 one of vaseline), absolute alcohol must be dropped upon them, in 

 order to make them unroll and lie fiat. After this they must be 

 exposed to a temperature of from 35° to 50° C. for about five to ten 

 minutes, in order to make the guttapercha viscous ; and after exposure 

 to the air for five to ten minutes, they must be put in a vessel with 

 warm absolute alcohol (from 40° to 50° C), to extract the paraffin. 

 This requires five to fifteen minutes. Alcohol must be used freely, 

 as it is not capable of dissolving much paraffin. When the alcohol 

 is saturated it can be filtered cold, and used as before. The prepara- 

 tion is now put in 70 per cent, alcohol and gradually into water, and 

 coloured at discretion. After the washing it is put in absolute 

 alcohol, in order to withdraw the water ; and, finally, oil of cloves is 

 dropped upon it to soften the guttapercha ; and it is finally mounted 

 in balsam or some similar substance. (2) If the object has been 

 imbedded in celloidin, as is now very often done, the sections are also 

 laid on the layer of guttapercha, and benzine or chloroform dropped 

 on them, by which means they stick fast. After they are dried, 

 they are coloured, and finally put in absolute alcohol, and treated 

 with oil of cloves (in drops), by which the celloidin is dissolved. 



* Zool. Anzeig., vi. (1883) p. 21. t Ibid. % Ibid., pp. 51-2. 



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