HOOKWORM OVA IN F^CES 



329 



central portion from the shell. Formed stools are more satisfactory for examination 

 than the liquid ones resulting from a dose of salts. Put about 2 drops of water or 

 i% trikresol solution in the center of a glass slide and emulsify in it as much of the 

 faeces as is held by the spatulate end of a wooden toothpick. A small piece of wood 

 or a match stick will answer. These preparations can be readily examined without 

 a cover-glass, using a %-inch objective, with a i-inch ocular. 



It is usually stated that about 500 worms must be present for several months 

 to produce symptoms. Grassi has thought that the presence of 150 eggs in o.oi 

 gm. faeces indicates the presence of 1000 worms, of which 25% would be males. 



V)_ 



2 







tt~ 



U-^ 



i- 



0" 



o- 



ORAWN TO .C.ALC x IOO O 



A.- Median focus BrSurf&ce focus 



ArShowind f/ 

 sides syif 

 metrically 

 convex 



Oxyuris 



vermicularis A.B. 



DrAtypicoJ. unfertilized 



e,? (ftftcr Looss.lQQ^J 



Strongylus 

 subtilis ' 



(fcf tr Looss, 



-."Without outer 



t*H I "* .!"'/( i*\ Tn^rMOiA TITIC iBf sJ& 



^^ Embryo 



ry ,-, ^ in stool 



^^/ An _y \fl^eri2to48 



A0chylostonicx r AgchyibstomS 



Trir*hi iri K ^f^S&T* 3 ^* 1 '" 2 ^ Jn'froshauxjl Abol t^ t i9o? S ) r 

 trtcjP-- Strongyloides 



(Origi 



FIG. 77. Nematode ova. 



There may be as many as 4,000,000 eggs in a stool. Bass has proposed the fol- 

 lowing method for the examination of faeces for ova. 



The faeces, which have been made fluid, should be centrifuged and the supernatant 

 fluid containing vegetable debris poured off. The sediment contains hookworm 

 eggs. Then pour on sediment a calcium chloride solution of sp. gr. 1.050. Again 

 centrifuge and decant. Next add calcium chloride solution of a sp. gr. of 1.250 and 

 centrifuge. This brings to the surface the hookworm eggs which may be pipetted 

 off. As a rule, the finding of hookworm eggs is very easy without such a technic. 



In certain cases, where a microscope is not available, the diagnosis may be made 

 by finding the worms in the stool following a thymol treatment. 



