XXIII, 2. Hub er: Metliod of preparing large Numbers of Sections. 10 1 



of the paraftin-ovcn. Tlic tissiic-hlocks and tlic paraffiii to l)c used 

 for embedding are kept in ])artial vacuum for about an lioiir, the 

 timc depending somewliat on their size and character. Expcrience 

 lias shown tliat pieces of tissiic thiis treatcd are bcttcr i)ernieated 

 by the jjaraflin tlian when embedded aftcr the metliods generally 

 in use, and lurthcr, and what is of equal iniportance, tlie ronsistancy 

 of the paraffin used f«>r enibedding is greatly improved. The pieces 

 of tissue with the ])araftin thus treated are pourcd into a Pirriu or 

 Esmauch's dish coated on the inside witli a tliin layer of glycerin, 

 and the pieces of tissue arranged ou the bottom of the dish. The 

 paraftin is then caused to liarden quickly by fioating the disli on 

 cold water and inimersing it as soon as the paraftin lias congealed 

 sufticiently to admit of this. After complete hardening tlie i>araftin 

 block thus obtained is cut into pieces as desired. Paraftin-blocks 

 containing one or several pieces of tissue even to the size of '.\ cm 

 by 1*5 to 2 cm are then readily cut serially on an automatic Zimmer- 

 mann microtome, Minot pattern (Leipzig), or better still on a Mixot 

 automatic rotary microtome (Bausch and Lomb) if the tissues are 

 well embedded and the paraffin is of the right consistency. 



Flattening paraffin sections and fixing to plate. In Hat- 

 tening out the paraffin sections and fixing them to the glass-plate 

 preparatory to removing tlie paraffin and Converting them to celloidin 

 sections we have found the following procedure very useful. In 

 Order to use conveniently the warm -water method of flattening ])a- 

 raffin sections, the apparatus shown in fig. 1 was devised. As inay 

 be ascertained from this figure, this consists of a rectangular tray, 

 supported by three legs the height of one of which may be adjusted. 

 This tray is constructed of copper, lined with tin and measures 

 18 cm by 12 cm with sides 3 cm high (size is arbitrary). To the 

 bottom of the tray are fastened three bridges about 1 cm liigh and 

 it is provided with an outflow, placed in one corner. A desired 

 number of glass-plates, 1(5 cm by 10 cm form a part of the equip- 

 ment. On using this apparatus, the tray is fiUed to a depth of 

 about 2 cm with distilled water or with a water- dcxtrin Solution 

 (see below). The distilled water used should be vigorously boiled 

 and allowed to cool before using to prevent the formation of bubbles 

 on using. The method may be combined with the Obregia-Gulland 

 procedure in one of two ways. Obregia's sugar-dextrin Solution is 

 prepared as follows : 



