1895.] MICROSCOPICAL JOURNAL. 121 



parts of collodion with one of castor oil — the per cent of the 

 collodion is not given. Sections are arranged on those prepared 

 slides and coated with a thicker solution, — collodion concen- 

 tratum duplex 2-3 parts, castor oil 2 parts ; no warming is 

 required, but the slide is put direct into a bath of turpentine 

 for 2 to 10 hours to dissolve out the paraffin. 



While working during the past year with serial sections, 

 great trouble was experienced with Mayer's albumen method, 

 and after some experimentation, the following plan was adopt- 

 ed : A layer of Mayer's albumen was spread on the slide and 

 the sections arranged. Then a wash I per cent collodion was 

 spread over the surface evenly with a camel's hair brush. 



This is allowed to dry, which takes place in about one 

 minute, but a longer time does no harm ; practically, one slide 

 dries while the next is being prepared. During the drying 

 many small air bubbles appear, the presence of which indicates 

 the right degree of dryness ; these do not cause any inconven- 

 ience, as they disappear during the subsequent processes. 



When dry the slide is put up, without heating, into a jar of xy- 

 lol or benzin for ha,lf an hour or more, to dissolve the paraffin. 

 A stay of several hours in the liquid will not injure the tissue. 

 The paraffin may be removed in 3 to 5 minutes by constantly 

 moving the slide in the benzin. The benzin or xylol is removed 

 by 95 per cent, alcohol, and the sections are then stained and 

 mounted as desired. 



It was found best to have the liquid for removing the para- 

 ffin as fresh as possible, or else the thin film of coUodion 

 retained a sufficient amount of it to render the surface greasy ; 

 benzin was tried and proved in every way to be as satisfactory 

 as xylol. Owing to its cheapness it is possible to use benzin in 

 much larger quantities than xylol, and the requisite degree of 

 freshness is easily obtained. 



Many slides were prepared without the preliminary coating 

 with albumen, and in all cases the collodion coat was sufficient 

 to keep the sections fastened to the slide, but owing to the well 

 known uncertainty in making a film of collodion adhere to 

 glass, the albumen was used as a safeguard against failure, the 

 alcohol in the collodion serving to coagulate the albumen. Dif- 

 ferent per cent solutions of collodion were tried and mixtures 

 varying in the proportions of ether and alcohol. No difference 



