ADDENDA. 405 



used ; run off the excess ; allow the plates to dry slowly in a hori- 

 zontal position and protected from dust. 



Arrange the series of sections in rows on the plates. Place the 

 plates in a paraffin-oven, which is kept at a temperature slightly 

 above the melting-point of the paraffin employed, and leave it there 

 for a few minutes, when the embedded tissues stick fast to the 

 prepared surface. 



Remove the surplus paraffin with xylol or naphtha, and then 

 wash with methylated spirit or absolute alcohol. 



The spirit is run off, and the plates are covered with the following 

 celloidin solution : 



Phytoxylin 6 grm. 



Absolute alcohol ..... loo cc. 

 Pure ether loo ,, 



The plates are placed horizontally. After the thin sheet of celloidin 

 solidifies, run a knife along between the rows of sections, and allow 

 further evaporation to take place. 



When the sections are required plunge the plate into water ; the 

 ribbons float off as the sugar is dissolved. The ribbons may be 

 stained with any reagents except those which dissolve or overstain 

 celloidin. Stain with very dilute Ehrlich's acid-hsematoxylm (p. 

 69), and then wash in dilute eosin. Dehydrate the sections, and 

 clarify in a mixture of xylol 3 parts and carbolic acid crystals i part, 

 and mount in balsam. We have tried this method, as recom- 

 mended by Gulland, and find that it works very well. Moreover, 

 we found that the sections, after being floated off, can be kept in 

 80 per cent, alcohol until they are required. 



