188 Hub er: Method of preparing large Numbers of Sections. XXIII, 2. 



A satisfactory and simple method for manipulating large mimbers of 



parafrin sections, — paraftin embedding and sectioning requiring less 



time and giving on the whole far better resiilts for tlie majority of 



tissues and organs thau celloidin embedding — woiild tberefore 



seem desirable. 



Several methods have been devised to obviate the necessity of re- 

 peated handling of Single sections wliile staining large nuiubers of sections. 

 Weigert (1) suggested a method, especially recomraended for the prepara- 

 tion of serial sections of the central nervous System to be stained after 

 his myelin stain, which is however equally applicable to celloidin sections 

 of any tissue, in the execution of wliich the celloidin sections are arranged 

 as desired on glass plates which have been coated with a thin layer of 

 celloidin which has been allowed to dry and are then covered by another 

 thin layer of celloidin. The sections are thus embedded in a thin sheet 

 of celloidin, which with all the contained sections may be manipulated as 

 a Single section during the staining procedure. Obregia (2) modified this 

 method so as to make it applicable both for celloidin and paraffin sections. 

 The procedure recommended by him consists in coating glass-plates with 

 a thin layer of sugar-dextrin Solution. These plates are then placed for a 

 time in a warm oven. The celloidin sections are then arranged on such 

 a plate as recommended by Weigert and are covered by a thin Solution 

 of photoxjdin in equal parts of alcohol and ether. The excess of this 

 Solution is allowed to drain olf , after which the thin layer of photoxylin 

 on the evaporation of the ether and alcohol forms a thin sheet. On now 

 placing the plate into water the photoxylin sheet becomes loosened, the 

 sections adhering thereto. Obregia calls especial attention to the fact 

 that this method is also applicable to parafhn sections. The method as 

 recommended is in the main as follows. The paraffin sections are arranged 

 on the dried sugar-dextrin coating of the glass-plate and slightly pressed 

 against the plate with a brush. The plate is then placed in the warm 

 oven (57^ to 60^) for ten minutes, in which on the softening of the paraftin 

 the sections flatten out. The paraffin is removed with filter paper and 

 then xylol and this with absolute alcohol and the plate with the adherent 

 sections covered by a thin layer of the photoxylin Solution. After drying, 

 the plate is placed into water in which the photoxylin sheet with the 

 adherent sections separates. Gulland (3) has modified, though immaterially, 

 the method suggested by Obregia so far as pertains to the plating of 

 paraffin sections, and recommends strongly its use in the preparation of 

 class material. In order to save time, he recommends that several pieces 

 of tissue be embedded in one paraffin block and cut on the "rocking 

 microtome". The sugar-dextrin Solution used is that recommended by 

 Obregia. Plates of a desired size are covered on one side with a thin 

 layer of this Solution and allowed to rest horizontally for two or three 

 days to enable the sugar-dextrin Solution to dry. On such a plate the 

 ribbons of paraffin sections are arranged and placed for a few minutes in 

 a warm-oven with a temperature slightly above that of the melting point 

 of the paraffin used. The melted paraffin is removed with naphtha and 



