362 



ELEMENTS OF BIOLOGY 



away. The mouth parts of the adult are adapted for piercing. The 

 salivary excretions contain a substance which prevents the clotting 



Fig. 217. — Diagram of the life history of a mosquito. 



of the host's blood and thus permits the fine mouth tube to extract 

 blood from the puncture. The malarial parasite, Plasmodium, which 

 was discussed in detail earlier (p. 75) is harbored in the salivary 



