176 TROPICAL MEDICINE AND HYGIENE 



Most of the other intestinal parasites are only passed 

 after the use of powerful anthelmintics thymol, san- 

 tonin, oil of male fern, eucalyptol and chloroform, and 

 the like or occasionally as a result of brisk purgation. 



For these worms the best method of diagnosis is the 

 microscopic examination of the faeces for eggs or 

 embryos. 



This examination is a simple one. A portion of the 

 fasces is placed on a slide and covered with a cover-glass 

 of medium thickness, and the faeces "squashed" out 

 into a thin enough layer to be transparent. If the faeces 

 are too hard to be compressed a little water may be added, 

 but if possible this should be avoided. If the motion is 

 a fluid one it should be allowed to stand, and a portion 

 of the deposit taken up with a pipette, as the eggs sink. 

 Where measurements are essential the method of com- 

 pression must be avoided, as eggs are easily distorted. 



Most of the eggs found in human faeces are readily 

 recognized. The oncospheres of the tapeworms are 

 recognized by the thick, radially striated embryonic cap- 

 sule, and the embryo with six hooklets in the interior. 



The eggs of the Bothriocephaloidea, Fasciolidae and 

 Paramphistomidae all have a capsule with an operculum 

 and lid. The contents are yolk-masses and the unde- 

 veloped ovum. Most of the egg-capsules are coloured 

 yellow or brown, but those of Bothriocephahis latus are 

 nearly colourless. To differentiate between the eggs of 

 different flukes measurements are required. 



Eggs of the Schistosomidae contain a fully developed 

 miracidium. In Schistosomum hcematobium the egg- 

 capsule has a terminal spine ; in S. mansoni the spine 

 is lateral, and in S. japonica there is a one-sided thickening 

 surmounted by a small knob representing the " spine." 



With the Nematode eggs there is great variation. The 

 characters of the capsule and of the egg-contents render 

 discrimination possible. 



In Ascaris lumbricoides the egg-capsule is thick and 

 usually coated over with albuminoid material stained 



