APPENDIX 



COLLECTION AND PRESERVATION OF ANIMAL 

 PARASITES 



INTESTINAL PROTOZOA 



The various intestinal Protozoa cannot be prepared satis- 

 factorily by methods such as those used in blood or bacteriological 

 work, which permit of drying at any stage. They must be 

 fixed while still moist and carried through much the same pro- 

 cedure as that used for animal tissues in general. 



A small amount of fresh fecal material is taken on an applicator 

 stick or a glass rod, or a bit of intestinal mucosa or other tissue 

 taken in forceps, and quickly smeared over a thoroughly cleaned 

 slide. If a stool sample should be very fluid, it is desirable first 

 to cover the slide with a thin film of egg albumen. The smear 

 preparation should be thicker than for ordinary bacteriological 

 work and should be passed immediately into the fixing fluid. 



For general work a very convenient technique is that of fixing 

 in Bouin's picro-formol (p. 113) for 10 to 30 minutes, washing in 

 several changes of 70 per cent alcohol to remove the excess picric 

 acid, rinsing in water, and staining for a few minutes in a weak 

 solution of Delafield's haematoxylin. The intensity of the stain 

 should be controlled by rinsing and examining in tap water. 

 Then dehydrate in ascending grades of alcohol; pass from 80 per 

 cent into a 0.1 per cent eosin in 95 per cent alcohol if a counter- 

 stain is wanted. Rinse in 95 per cent alcohol, clear in carbol- 

 xylol, and mount in balsam. 



A standard and, once mastered, the best method for prepara- 

 tion of permanent mounts is that of fixation in warm Schaudinn's 

 fluid and staining in iron haematoxylin. 



Schaudinn's fluid is composed of 2 parts of saturated aqueous 

 solution of corrosive sublimate, and 1 part of 95 per cent ethyl 

 alcohol, acidulated by the addition of glacial acetic acid. A 

 convenient quantity is: 



Saturated aqueous solution of corrosive sublimate. ... 65 cc. 



95 per cent ethyl alcohol 33 cc. 



Glacial acetic acid 2 cc. 



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