HIRUDINIASIS 323 



CESTODES. 



Preservation. 



(i) Shake gently in i per cent, saline. 



(2) Add formalin to this to make a 10 per cent, solution and shake 

 pfentlv until thev die. 



The specimens can be stored in 10 per cent, formalin. 



To stain and mount Segments. 



(i) Place alive in weak glycerin, faintly coloured with carmine, and 

 leave until stained, or dilute hiemalum may be used. 



(2) Press between two slides and drop into methylated spirit. 

 They should remain in this for twenty-four hours. 



(3) Remove the pressure and place the segments in fresh methylated 

 spirit for an hour or so. 



(4) Clear in oil of cloves. 



(5) Pass through zylol and mount in balsam. 

 Creosote may be used to clear instead of oil of cloves. 



The Preservation of Helminth Ova in Faeces. 



Method (i). 



Alcohol, 70 per cent., with 5 per cent, glycerine added, is raised to 

 boiling point. 



Fluid faeces, or faeces made fluid by dilution with saline, are poured 

 into the boiling alcohol, stirred, and then set aside to inspissate in a 

 warm place. When the fasces have become a sticky mass, sufficient 

 pure glycerine is added to make a soft paste (Leiper). 



Method (2). 



To fluid faeces add equal parts of Langeron's lactophenol. This 

 latter consists of carbolic acid one part, lactic acid one part, glycerin 

 two parts, and water one part. 



Shake vigorously. 



This mixture will form a pasty jelly and will keep indefinitely. 



A permanent preparation can be made at any time by stirring a small 

 portion into a loop of melted glycerin jelly on a slide, a cover glass is 

 placed on the jelly, and when this is set the preparation is completed by 

 sealing with gold size (Leiper). 



HIRUDINIASIS. 

 DEFINITION. 



An invasion of the mouth, nose, pharynx and larynx, or an afi'ection 

 of the skin by leeches, a group of unsegmented worms allied to 

 Chastopoda. 



