QUEKETT MICROSCOPICAL CLUB. 395 



from the dorsal surface of the thorax. The perfect gnat emerges^ 

 from the pupa case while it floats on the water. Culex carries 

 no disease in this country, neither does Stegomyisi, hut Anopheles 

 maculi'pennis , which is also found in Britain, is the notorious 

 carrier of malaria. Usually there are very few cases of malaria 

 here, but now there are thousands of troops suffering from this 

 disease, and it is very desirable that these men should be placed 

 in districts in which Anopheles is not found until they have 

 recovered. Mr, Offord then described the points of difference 

 between Culex and Anopheles. In the case of Anopheles the eggs 

 are not laid fastened together like a raft. The breathing-tube of 

 the larva is so short that the larva floats in a horizontal position 

 at the surface of the water when breathing, instead of hanging^ 

 head downwards at an angle of 45 deg., like Culex. The imago 

 has no scales on the body, and the resting positions are very^ 

 different, Culex resting with the head and tip of the abdomen 

 down and the thorax farthest from the surface it rests on, while- 

 Anopheles rests with the head and body almost in a line, the head 

 being down and the tip of the abdomen raised. Mr. Offord then 

 briefly sketched the life-history of the malaria parasite, showing 

 how the sporozoite is introduced into the human blood during 

 the biting of the mosquito, enters a blood corpuscle, and develops 

 into an amoebula, which grows into a rosette and divides into 

 merozoites. The corpuscle then disintegrates, and the free 

 merozoites invade fresh corpuscles. After several cycles mero- 

 zoites develop into male and female crescents, which undergo no 

 further change until they again enter the stomach of a mosquito, 

 when after further developments an ovum is produced, which 

 elongates and bores through to the outer wall of the stomach, 

 where it forms a cyst. Sporozoites are formed in the cyst, which 

 bursts and they escape, those which reach the salivary glands 

 passing into a human being and starting the cycle again. The 

 lecturer then described the slides and specimens, most of which 

 were very kindly lent by Mr. Lang of the Natural History Museum . 

 He also read some notes which Mr. Lang had written, describing 

 the specimens, and giving some interesting details of the life-history 

 of gnats. Mr. Offord recommended members to notify the Museum 

 of localities where they found specimens of Anopheles, so that they 

 might be avoided by men suffering from malaria. 



Mr. James Burton gave an interesting account of the feeding. 



