72 THE AMERICAN MONTHLY [May 



the canal-system but of an unnaturally bright color. 

 Madder gives a more natural color. Methylene-blue 

 works well with fresh specimens only. A four per cent 

 solution of formic aldehyde is far better than alcohol if 

 the newly caught animals are at once put into it. It will 

 dissolve out the salt. The Medusae retain their form 

 well. Their delicate parts can be arranged without 

 tearing except that the delicate fringe of Aurelia may 

 prove too rigid to be extended. Having removed the 

 salt and stained the specimen the lantern-slide glass 

 should be put into a developing dish and the animal 

 floated out and arranged under the liquid. The speci- 

 men may be half an inch thick in the centre and no 

 attempt should be made to dry it at once since the 

 greater part of the included liquid will diffuse out and be 

 drained off. If the liquid comes off badly spread a solu- 

 tion of gum over the animal. When the edge dries 

 cover it with a ."^trong clear solution of gum to which a 

 little glycerine has been added to make it less brittle. 

 This process is continued till the whole specimen is 

 covered with gum. Keep it then for some days to 

 permit the gum to soak in and the buM)les to disappear 

 by absorption which have not been removed mechanically. 

 If kept in a developing dish over a little water covered 

 by a close-fitting glass plate, a long growth of mould 

 may appear in a single day but if alcohol is substituted 

 for half the water they may remain out for weeks without 

 mould appearing or alteration in the gum taking place 

 which latter would occur in the use of strong alcohol. 

 Do not dry too quickly but anneal the specimen since con- 

 traction may cause them to crack and scale off from the 

 glass. 



Coloring matteb. — Dilute sulphurous acid is very 

 useful to destroy the coloring matter, especially in the 

 case of small fishes. If a plaice, 2i inches long, is kept 

 in alcohol and later in dilute sulphurous acid for a few 



