264 TROPICAL MEDICINE AND HYGIENE 



Normal blood : Weight about ^ of the body weight, say, 

 9 pints or 5,000 cubic centimetres. 



Red corpuscles : About 5,000,000 per cubic millimetre. 



Leucocytes : 6,000 to 8,000 per cubic millimetre. 

 Of these 65 to 75 per cent, are polymorphonuclear leucocytes. 



,, 5 ,, 10 ,, ,, large mononuclear. 



I 5 2 5 i i lymphocytes, but number 



varies according to the 

 stage of digestion. 



,, i ,, 3 ,, ,, eosinophiles. 

 Malaria. Diameter of " spores " or merozoites : 



Benign tertian 1-5 M . 



Quartan ... ... ... ... 1-75 ^ 



Subtertian ... ... ... 0-7^. 



Full-grown parasite, sporocyte or schizont : 



Benign tertian ... ... ... 8*5 /*. 



Quartan ... ... ... ... b p. 



Subtertian ... ... ... 4-5 ^. 



Full-grown zygote =501060/4. 



Sporozoite = 14 M . 



Leishman-Donovan body ... = 2-5 to 3-5 ^ x 1*5 to 2/4. 

 Amoeba coli ... ... ... ... Up to 50 ^ 



Encysted form 151020^. 



Lamblia intestinalis ... ... ... Up to 15 p. in length. 



Encysted form 13 ^ x 7 p.. 



Trichomonas Jiominis ... ... ... 3 /* to 20 /*. 



Encysted form Up to 15 p. 



III. TICKS. 



Blood-sucking Arthropods are found also amongst the 

 Arachnidae, which in the adult stage are readily distinguished 

 from the insects, even from the wingless insects, by the 

 presence of four pairs of legs and the absence of antennae, 

 whilst the orifice of the mouth is a small slit. 



The blood-sucking groups are the IXODID^E. 



IXODID.E have either a hard and chitinous or thick, leathery 

 skin. The mouth-parts consist of a central hypostome armed 

 with teeth projecting backwards, and on each 'side a powerful 

 chelicera, also armed with teeth projecting backwards, chelicera, 



