THE WEB OF LIFE 



363 



FIG. 57. A common mosquito, Anopheles maculipennis (female), 

 which carries the Protozoon causing malaria. (After Nuttall.) 



coincidence. Avicenna refers to it in connexion with a 

 plague in Mesopotamia about A.D. 1000. But the identity 

 of the diseases in rat and man was not established till 

 1894, when the Bacillus pestis was discovered by Yersin and 

 Kitasato. This bacillus is a minute rod-like body with 

 rounded ends, about ^WQ-Q of an inch in length. It is fatal 

 not only to man, but to rats, mice, guinea-pigs, rabbits, 

 hares, ferrets, cats, monkeys, and American ground 



