ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 819 



rendering them (after cooling) sufficiently hard for the process of 

 sectioning. 



Glycerin and Gelatin. — Gelatin 1 part ; distilled water 6 parts ; 

 glycerin 7 parts. For preservation a little carbolic acid (1 gram for 

 100 grams of the mixture) should be added. Objects are transferred 

 directly from water to tlie melted mixture, and after complete satura- 

 tion imbedded in paper boxes. After cooling the objects thus imbedded 

 are hardened in alcohol, then sectioned and mounted in glycerin.* 



Schiefferdechers Method of Imhedding in Celloidin. — Schieffer- 

 decker f uses two solutions, one of syrupy consistency, the other some- 

 what thinner. The celloidin plate is cut into small pieces and 

 dissolved in absolute alcohol and ether (in equal parts). Objects are 

 transferred from absolute alcohol,t first to the thinner solution, then 

 to the thicker. After remaining a few hours (or days, according to 

 the character of the object) in the latter, they are imbedded in paper 

 boxes. As soon as a hardened film forms on the solution in the box, 

 the whole is placed in 82 per cent, alcohol for 24-28 hours, and thus 

 rendered sufiiciently hard for cutting. 



Blochmann recommends imbedding on a cork rather than in a 

 paper box, as less celloidin is required, and as the cork is held more 

 firmly in the holder. One end of the cork is made rough and sur- 

 rounded by a strip of paper, which is made fast by a pin as shown in 

 fig. 137. The roughened surface of the cork is wet with absolute 

 alcohol, and then the object is imbedded in the usual 

 manner. In order that this small box may sink in Fig. 137. 

 alcohol, in which it is placed for hardening the 

 celloidin, it may be weighted with a small lead ball 

 fastened to the cork by a needle. 



In cutting, the knife is kept wet with alcohol 

 (70 per cent.). The sections may be placed in water 

 or in alcohol and afterwards stained with carmine 

 or haimatoxylin, in which the celloidin is only a little 

 or not at all stained. Anilin dyes colour the celloidin, 

 and therefore should not be used. 



The sections can be ' mounted in glycerin or in 

 balsam, but in the latter case they must be anhydrated 

 with 95 per cent, alcohol, as absolute alcohol dis- 

 solves the celloidin. They should be clarified in 

 bergamot-oil or origanum-oil (clove-oil dissolves the 

 celloidin). 



Objects imbedded in celloidin can be preserved ready for cutting 

 for a long time in 70-80 per cent, alcohol. 



Imhedding in Paraffin. — The object is transferred from absolute 

 alcohol to chloroform, and left till the alcohol has been entirely 

 replaced ; it is next placed in a shallow vessel with a small quantity 

 of chloroform and enough paraffin added in fine pieces to cover it 



* Tliis method was recommended by Kaiser, Bot. Coiitralbl., i. (1880) p. 25. 

 t Arch. f. Anat. u. Physiol. 1882, p. 191). 



X If the oVjjectH are penetrated with difficulty thoy may bo transferred from 

 absolute alcohol to ether, then to the celloidin solution. 



