THE PATHOGENIC PROTOZOA 183 



nature have also been reported in pneumonia and scarlet 

 fever. 



Luetin. Cultures of T. pallidum are ground up with 

 normal saline, heated to 60 C. for an hour and 0'5 per 

 cent, phenol added. Luetin is injected into the skin 

 of the arm and a positive reaction consists of the produc- 

 tion at the site of inoculation in forty-eight hours of a 

 diffuse erythema with sometimes the development of 

 a papule or pustule later on. In non-luetic cases a slight 

 erythema occurs. A positive result means no more 

 than that the patient has had syphilis, it does not indicate 

 that the disease is actually active. 



As a result of the administration of arsenical prepara- 

 tions in treatment, arsenic-resistant treponemes may be 

 produced. 



The Malarial Parasite. 



Plasmodium malarice or Hcemamceba malar ice is con- 

 veyed from man to man by mosquitoes of the genus 

 Anophelina, the commonest species of malaria carriers 

 being the Anopheles maculipennis, A. funestus, A. cos- 

 talis, A. sincnsis, and A. argyrotarsus. When at rest the 

 proboscis, thorax, and abdomen of the Anopheles form 

 a straight line, with the proboscis almost touching the 

 wall, and thus form an angle with the wall or other resting 

 surface. The resting CuUx, on the other hand, rests 

 with its body parallel to the resting surface. The ova of 

 the Anopheles are much smaller than those of other 

 mosquitoes, and are boat-shaped. Down the centre of 

 the body of a larva run two breathing tubes, the opening 

 of which is in the anterior part of the last segment, which 

 necessitates them floating horizontally at the surface of 

 water. The larvae of other mosquitoes hang down from 

 the surface. The female alone bites, generally at night, 

 and, in the event of the subject being malarial and the 

 parasite being ingested, its development is complete in 

 eight or ten days, when it is ready for successful inocula- 

 tion into a healthy subject. After the mosquito bite the 

 organism enters a red blood- corpuscle, being at first a 

 small, pale, nebulous, ill-defined body, which grows in 

 size and alters in shape, sometimes to a ring-like form, 

 developing black pigment granules, which exhibit slow 

 movements, and tend to concentrate while the amoeboid 



