The Microscope. 59 



Przewaski's Method of Imbedding in Paraffin.* — Dehy- 

 dration in absolute alcohol may be avoided by the use of the 

 following method, which is cheaper, surer and applicable to 

 larger masses : The piece is transferred from ordinary alcohol to 

 anhydrous aniline oil, or oil containing but little water, and is 

 to remain there for 24 hours. It is then transferred to chloro- 

 form, which penetrates it and dissolves out the aniline oil. After 

 a sojourn here of 24 hours it is placed in a solution of paraffin 

 in chloroform (40 per cent), then in melted paraffin, which should 

 be hardened immediately so that the tissue shall not become 

 brittle. 



Aniline oil may be deh^^drated by distillation or by placing in 

 it a small piece of caustic potassa. The oil gives the specimen a 

 3^ellowish amber, translucent appearance, which disappears as 

 the chloroform enters. This method has the additional advan- 

 tage of allowing the use of specimens not entirely dehydrated, 

 the chloroform taking the water when it is mixed with aniline 

 oil. The preparation is finished in the usual way. 



An Improved Live-box. f — It is frequently desirable to exam- 

 ine an object with a high power after it has been found with a 

 low one, and we all know how very fond living creatures 

 are of getting to the edge of the drop of water in which the}^ 

 are placed, and to shift them to the centre is frequently a tedious 

 work, and is often fatal to the animal. To remedy this defect 



te ' '>^.. ..:mM^ '{^mm:.Mmm 



I have had a live-box constructed, in which the glass tablet is 

 somewhat reduced in diameter, but the outer ring is enlarged suf- 

 ficiently to allow any high power to focus to the very edge of 

 the glass tablet, and the result is very satisfactory. An object 

 lying anywhere in the live-box can be reached by the condenser 

 from below, and by both high and low powers from above ; 

 besides which it acts as a very good compresser, capable of fix- 

 ing, without hurting, the smallest Rotifers, and when you know 



^Centralb. f. Allg. Pathol, u. Pathol. Anat.— Cf. Bui. Beige Mic. 

 fJour. Q. M. C. 



