200 



ZOOLOGY FOR MEDICAL STUDENTS 



CHAP. 



:ul 45-50 mm. in the female, and it is easily recognized by the fact 



that the anterior portion of the body forms a fine filament which is threaded 



h tin- intestinal lining and serves to anchor the worm in position. 



i an elongated ellipsoidal form and measuring about 52 p. 



in len-th by 23 //. in width (Fig. 90, A), pass to the exterior and if the 



go on developing to an advanced embryonic stage. If 



s \\allo\\ed at this stage which may last for a prolonged period the 



uorms hatch out in the alimentary canal of their new host and in 



about a month are mature and 

 producing eggs. 



OXYURIS 



0. vermicular is is a small 

 nematode ( 3-5 mm., 9 I0 mm.) 

 which occurs in the large intes- 

 tine of man and is the usual 

 cause of the complaint popularly 

 known as " worms " in children. 

 The female when ready to deposit 

 the eggs travels down the intes- 

 tine towards the anal openingand 

 the eggs are deposited either on 

 the skin or in faecal matter. If 

 swallowed there hatches out from 

 the egg a young worm which de- 

 velops into an adult like the 

 parent. 



FIG. 91. 



Trichocephalus trichiura 9x6. ax, Alimentary ANCYLOSTOMA 



canal ; g, uterus ; M, moutli. 



The Miner's Worm or Hook- 

 worm (Aucylostoma duodenale) although small in size ( about 10 mm., 

 is mm.) is yet a very dangerous parasite of man, for it is 

 liable to occur in the small intestine in enormous numbers and cause 



"1 anaemia, It occurs in practically all the warmer parts of the 

 world and is particularly prevalent in Egypt and some parts of India, 

 and in the Southern States of North America. In colder climates it is 



be introduced and flourish amongst workmen where the necessary 

 condition-, ot warmth and moisture are present, as in tunnels and mines. 

 In mining districts its appearance should always be borne in mind as a 



