EXAMINATION OF MOSQUITOS 781 



The preparation should first be examined under a low power of the microscope 

 and when a cyst is found a higher power or a ^ immersion lens is turned on. 

 If there is still some blood in the stomach it may be mixed with a 0'75 per cent, 

 saline solution : the blood flows into the liquid and the preparation is covered with 

 a cover-glass and examined for parasites. 



The examination of the salivary glands is more difficult, and the dissection should 

 be done with a lens. Fix the middle of the thorax by laying a needle horizontally 

 across it. then with a second needle gently tear away the head, taking the three 

 lobes of the salivary gland with it. 



The glands should be examined in the following solution : 



Distilled water, - - - 100 grams. 



Commercial formalin, 2 ,, 



Sodium chloride, 0*75 gram. 



Staining method. Dissect the stomach in a 0'75 per cent, solution of sodium 

 chloride : fix for 1 minute in osmic acid vapour, stain with picro-carmine and mount 

 in glycerin. 



Any parasites which may be present in the undigested blood in the stomach can 

 be examined by preparing a blood film with a drop of the saline solution in which 

 the stomach was dissected and staining in the manner described on p. 771. 



The sporozoi'tes can also be examined by gently pressing upon and rupturing one 

 of the oocysts into the saline solution in which the stomach was dissected and then- 

 examining a drop of the fluid under the microscope. 



Sections. The best method is to fix the whole mosquito. After removing the 

 legs and wings pour a little boiling acid perchloride (p. 189) on to it. The body 

 will break up into two or three pieces which can then be embedded in paraffin. 

 The sections must be cut very thin and should be stained with Bcehmer's or Heiden- 

 hain's hsematoxylin. 



Experimental inoculation. 



The disease can be reproduced experimentally by inoculating the parasite 

 into man : to ensure the success of the experiment it would appear best to 

 inoculate infected blood into a vein. Eight to ten days after the inoculation 

 parasites appear in the blood and symptoms of malaria develop. 



Man can be also experimentally infected with malaria by being bitten by 

 an Anopheles which has sucked the blood of infected persons. Manson 

 infected his son [and his laboratory attendant] neither of whom had ever 

 been out of England, by allowing them to be bitten by mosquitos fed on 

 malarial blood sent from Rome. 



Monkeys are immune to the human parasite and all attempts to infect the 

 lower animals have failed. 



It has not been possible to cultivate the hsematozoon outside the body. 



2. The hsematozoon of monkeys. 



Hsemamceba kochi. 



Koch, Kossel, Bruce and Nabarro, and Laveran have described an intra- 

 corpuscular hsematozoon in several species of monkeys but chiefly in 

 the Cercopitheci. In the fully grown form the parasite appears as a spherical 

 pigmented body : a rosette stage has not been seen. Monkeys cannot be 

 experimentally infected. 



3. The hsematozoon of bats. 



Dionisi has found an Hsematozoon of the genus Hsemamoeba (H. melani- 

 phera) in bats (Miniopterus scJireibersii). 



4. The hsematozoa of birds. 



Hsematozoa closely related to the hsematozoa of malaria have been found 

 in the blood of many birds (jays, magpies, rooks, crows, hawks, screech owls, 



