280 DE VOGEL. 



No other species is known to be capable of developing both in fresh water 

 and in partially evaporated sea water containing more than 5 per cent 

 sodium chloride. This species, M. rossii, therefore, is especially suitable 

 for determining the limits within which the quantity of salt contained 

 in the breeding places may or may nor render the mosquitoes produced 

 in them more or less liable to infection with malarial plasmodia. 



Suitable subjects for making infection experiments on mosquitoes are 

 rarely encountered among the sufferers from malaria in the Samarang 

 hospitals. Gametes are generally found only sporadically in the periph- 

 eral blood. Consequently, on October 25, 1908, when a female patient, 

 whose blood-smears under the microscope showed two or three Laveran 

 crescents in every field, applied for admission to one of the hospitals, the 

 opportunity was eagerly seized. 



The patient was a young native (Javanese) woman from the Karang Bidara 

 quarter situated within the district of malarial centers along the coast. She 

 was extremely anoemic, and had a spleen that reached to the umbilicus. The 

 pulse was regular. The temperature varied between 36° and 36.8°. Apprehend- 

 ing the ever-threatening pernicious attack, it was decided to give a dose of 

 0.500 gram of hydrochloride of quinine three times a day. This dose was admin- 

 istered daily from October 26 onward. 



Meanwhile, mosquito larva? were obtained along the coast from pools 

 containing water of varying concentration, from rain water, up to 

 solutions containing 1.6 per cent sodium chloride. After a few diffi- 

 culties had been overcome, the first mosquito was dissected with a positive 

 result; This was on November 3, and after the patient had taken 1.5 

 gram of quinine for nine days. The ■ insect had sucked the patient's 

 blood five hours previously. 



. The stomach, full of blood, was crushed under a cover-glass. When 

 examined under the microscope, worm-like, moving organisms which 

 resembled ookinetes were visible. The preparation was then stained, 

 according to Giemsa's method. Many spool-shaped elements were then 

 seen, with an intensively colored chromatin core in the middle and the 

 pigment compressed to one point in the spool. The picture exactly 

 resembled the illustrations of ookinetes in colored preparations given by 

 Schaudinn. Unfortunately, it is not known what percentage of common 

 salt was contained in the water from which this mosquito was produced. 

 Tbe following table gives the results of these experiments, together with 

 a few of the more important details : 



