2/6 



DISEASES DUE TO HELMINTHS 



labium. Here the parasites wait, and when an animal, usually man, 

 is bitten, the Microfilaria passes through Dutton's membrane, and 

 enters the wound made by the proboscis of the insect. When a fly is 

 fed upon vegetable matter, however, the MicrofilariiE will not pass 

 through. From the wound the embryo passes into the lymphatics, 

 where it becomes sexually mature, fecundation is affected, and new 

 generations of larv^ are poured into the lymphatic stream. These 

 then pass to the thoracic duct as described above. The embryos are 

 often harmless; it is the injured parent worm and the immature 

 products of conception that are dangerous. A man's blood may 



Mf. demarqiiayi in thick film, dried and stained with hsematoxylin. 6, unshrunken ; 

 7, shrunken. X i,ooo. (After Fiilleborn.) 



swarm with the embryos, and yet he may show neither signs nor 

 symptoms. 



To demonstrate the Microfilaria. — Take an ordinary blood slide at 

 night, place it at once in weak fuchsin, four minims to one ounce of 

 water, leave it for one hour, and examine it wet without a cover-glass. 

 To partly decolorize use weak acetic acid. 



To fix, stain Avith methylene blue for thirty seconds and examine 

 it wet. 



The haemoglobin is washed out, and the only coloured objects are 

 the leucocytes and the embryos. 



To keep them alive for six or seven d£iys, ring a cover-glass with 

 vaseline and place it upon the fresh specimen in the ordinary way. 



