XXIII, 2. Hub er: Methocl of preparing large Numbers of Sections. 189 



tliis is displaced with alcohol. The sections arc then covered with a thin 

 Solution of celloidin, its solvent allovved to evaporate and the plate placcd 

 into water in wliich the sheet of celloidin Avith the adherent sectit»ns 

 becomes loosened. By means of this Obregia-Gulland raethod, a desired 

 nnmber of paraftin sections are converted into celloidin sections, the cel- 

 loidin (or photoxylin) being in the form of a Single sheet which may readily 

 be manipulated in the various steps of staining, dehj'dration and Clearing. 

 Strasser (4) has moditied the original Weigert (1) method in another 

 direction , suggesting the use of paper Strips coated with gum Arabic 

 foUowed by a coating with collodiuiu , and to inake such strips adhesive 

 for paraffin sections a further coating with coUodiura (2 parts) and clove 

 oil (1 parti. The paraffin sections, which need to be free frora folds (and 

 to obtain such Strasser suggests the use of a section-stretcher) are ar- 

 ranged on these prepared strips of paper and are then covered with a 

 layer of the collodiuiu -clove oil Solution. Strasser (.5 — 6) has further 

 inodified and as he states, siiuplified Ins method, and calls special attention 

 to the ease with which paraffin sections thus fixed to strips may be stored 

 for a long time ready for future use. For the details of Strasser's method, 

 his especially constructed microtome and section-stretcher, the reader is 

 referred to the original publications. A further method, based on a ditferent 

 principle tlian the methods above enumerated, for staining large numbers 

 of paraffin sections , with the possibility of obtaining Single sections has 

 quite recently been recommended by Heidenhain (7). The method of 

 procedure suggested is essentially the same as that used for fixing sec- 

 tions to slides with the water-albumen method, except that thin mica-plates 

 (Glimmerplatten) of the required size are used. The mica-plates are 

 to be thoroughly cleaned, but without causing breaks or cracks. The 

 plates are then covered with a layer of water and albumen fixative or a 

 Solution of serum albumen. The ribbons of paraffin sections are arrangcd 

 on such plates and placed on a warming table modified from that described 

 by Born in Order to fiatten out the sections. As soon as this is accom- 

 plished the excess of water is allowed to drain oflf and the mica-plate with 

 the adherent sections placed in a warm oven with a temperature of 33*' 

 to 35°. After the evaporation of the water the paraffin is removed in the 

 usual way and the sections are stained as desired. The mica-plates are 

 cut up as desired after staining and Clearing the sections. This method 

 has not as yet been tried in this laboratory , but would on a priori 

 grounds seem open to certain objections, as perfectly -clear mica-plates of 

 any size are not readily obtained and only such would, it would seem, 

 meet the requirements. All the other methods mentioned possess certain 

 disadvantages as may be attested by the fact that they liave not met 

 with general acceptance. With the Obregia-Gulland method, the paraffin 

 sections if at all folded are often difficult to flatten out and the Strasser 

 methotl is not easy of raanipulation and requires special apparatus for its 

 most successful Operation. For this reason , we have been in this labo- 

 ratory for some time engaged in modifying raore particularly the Obregia- 

 GuLLAND method with an endeavor to make it more generally satisfactory 

 and easy of manipulation so as to rid it of certain of its objectionable 



