THE EXAMINATION OE EJECES 637' 



An ethereal solution of acid hiemalin is obtained. 

 If altered blood is present it is seen by means of the spectro- 

 scope, 



THE DETECTION OF OVA. 



This is all-import£int. Their appearance is described in the section 

 on " Diseases due to Helminths," but to facilitate laboratory work a 

 concise description will be given here. 



A moist stool needs no water; to a dry one add a little water and 

 place a small portion on the slide, and press it out gently with a cover 

 glass. As eggs are heavier than \\ater more will be at the bottom of 

 a water stool. 



Many eggs of Ascaris matter little as a rule, and those of Tricho- 

 cephalus dispar less, but a few ankylostomes are of considerable 

 importance. 



A § objective should diagnose all. 



(i) Ascaris lumbricoides. — Ovoid or round with a double contour. 

 Thick clear yellow shell. May or may not be surrounded by 

 an irregular protective coat of stained albumin, granular 

 yellow contents not completelv filling interior. The shell 

 resists formalin. 



(2) Trichocephalus dispar. — Small oval yellow eggs, double con- 



tour, a distinct " plug " of mucus at each end, a granular 

 interior and a very thin unstained inner capsule. 



(3) Oxyuris vermicularis. — Xot unlike the ankylostome ^gg, but 



somewhat flattened, and contains a well-formed embryo when 

 freshly passed. 



(4) Ankylostomum duodenale. — Unstained, a single thin trans- 



parent capsule, segmented nuclear matter into two to forty- 

 eight cells, does not fill cavity, an embryo in about forty-eight 

 hours. 



(5) Trematodes. — These are yellow, small, and have a lid or 



operculum, which may be split olT. Their size differentiates 

 them. 



(6) Chlonorchis sinensis. — This has a " jug " shape, with a distinct 



lid above and a small spine below. 



(7) Schistosoma haematobium (from urine usually). — Large ter- 



minal sharp spike, thick shell containing embryo. Add a 

 little water to the slide and the embryo will come out. 



Schistosoma mansoni as above with a lateral spine. 



Schistosoma japonicum has a knob laterally, no spine and no 

 operculum. 



(8) Oncosphere of Cestode. — A radical striation of the thick 



capsule with three pairs of booklets in the central embryonic 

 matter readily distinguishable from other ova. 



