PABASITISM IN RELATION TO BIRDS. 45 



contents of the alimentary system were poured into a large vessel, 

 and a small quantity of a fixing agent * added ; any small and 

 transparent Tapeworms were by this means caused to become 

 opaque and easily seen. 



The Tapeworms obtained were allowed to wash in running 

 water for about two or three hours, during which time they 

 become extended to the full. 



Fixing. — Next comes the fixing, which is performed by 

 immersion of the worms in some fixing solution for a certain 

 length of time. The fixing solution which acted best was the 

 following : — Five per cent, corrosive sublimate, one per cent, 

 acetic acid, ninety-four per cent, water. 



The worms were allowed to remain in this fixing solution for 

 about twenty minutes. Of course, in the case of the large ones 

 more time was allowed. 



Washing. — They were next transferred to running water to 

 thoroughly wash out the fixing, a time generally extending over 

 about twelve hours. 



The next process was to pass the worms through varying 

 grades of alcohol, commencing with sixty per cent, alcohol, then 

 seventy per cent., next eighty per cent., finishing with ninety per 

 cent. The time of immersion in each case being about twice the 

 former ; that is, four hours in sixty per cent, alcohol, and eight 

 hours in seventy per cent., sixteen hours in eighty per cent, 

 alcohol. 



Staining. — From the ninety per cent, alcohol the worms were 

 passed into some suitable staining solution. Alcoholic borax- 

 carmine was found to be most suitable for staining in toto ; 

 methyl green was also used, but not so successfully. After being 

 in the staining solution for about twenty-four hours, the speci- 

 mens were toned down to the requisite depth of colour by 

 immersion in sixty per cent, alcohol, to which nitric acid had been 

 added — three drops of acid to one hundred cubic cms. of alcohol. 



Dehydratin.—The stained Tapeworms were then again run 

 through the varying strengths of alcohol, ending up with abso- 

 lute alcohol to rid them of the water. From the absolute alcohol 

 they were next transferred to xylol as a clearing agent. Oil 

 of cloves was found to make them too brittle for mounting. 



* Two per cent, corrosive sublimate in alcohol. 



