PRESERVATION FOR MUSEUM PURPOSES 107 



frequently be found expedient, however, to preserve the superfluous 

 material. 



The best fluid for preserving specimens for museum purposes is 

 undoubtedly alcohol; or, in certain specified cases (Nematodes), 

 alcohol and glycerine. The fixing reagents are identical with those 

 given above, and to these alcohol may be added. If employed with 

 caution, it is very useful for fixing Trematodes and Cestodes, and may 

 also be used for Nematodes and Acanthocephales ; 70 per cent, alcohol 

 warmed to a temperature of about 60 is the best. Examples of new or 

 rare species should never all be fixed with metallic salts or with acids. 

 A certain proportion of the individuals should invariably be killed 

 with alcohol, for it is almost certain that the newer methods of fixing, 

 with metallic salts and acids, are liable to change the tissues. In 

 consequence of this the objects become so brittle that, after they 

 have been kept for a certain time in alcohol, it is impossible to handle 

 them. Absolute, or very strong, alcohol, should on no account be 

 used ; the best strength is 60 per cent, or 70 per cent., and it should 

 be slightly warmed. For permanent preservation, specimens should 

 be put into 80 per cent, to 90 per cent, alcohol, in cylindrical glass 

 bottles with wide necks. These should be furnished with glass 

 stoppers, not corks, as the alcohol extracts both pigment and acid 

 from cork, and these will in time affect the object. For the sake of 

 convenience, small varieties of worms may be kept in glass tubes 

 closed with cotton-wool, no air being allowed to remain between the 

 surface of the alcohol and the wad. The tubes are stored, wad 

 downwards, in a bottle filled with alcohol. Under certain conditions, 

 larger varieties, such as Filarise and thin Cestodes, are also enclosed 

 in tubes before putting into bottles, though this is unnecessary in 

 the case of the robuster sorts. Long Cestodes may be coiled spirally 

 round a tube ; the head and tail ends should be fastened with a 

 thread, and the whole then enclosed in a cylindrical bottle containing 

 alcohol. 



Dry preparations of large Cestodes are very instructive and are 

 useful for purposes of demonstration. The worms should be cleaned 

 and, if not already dead, they should be killed in weak alcohol. They 

 are laid upon a sheet of black glass to dry and carefully protected from 

 dust. Worms with a large proportion of calcareous bodies in the 

 parenchyma make very striking specimens, as they dry chalk-white. 

 The objects may be kept in square glasses, or they may be framed like 

 pictures. 



There is a quick method of preserving intestinal worms in large 

 numbers, which is particularly useful when travelling, or when some 

 chance puts a collector in the way of specimens which interest him. 

 The bowel is opened up along its length ; large worms are removed 



