882 PATHOGENIC MICROORGANISMS 



inoculated with 10 c.c. of urine came down. Examinations of the 

 organs revealed them in only one case in the kidneys. 



Working with mosquitoes, Noguchi allowed Stegomyia calopus 

 to bite yellow fever patients during the early stages of the disease. 

 He placed the arm of a patient into a cage containing 200 to 300 

 mosquitoes hatched from the larvae, and allowed the mosquitoes 

 to feed until the females were full of blood. Twenty-three days 

 after feeding on the patient, the mosquitoes were allowed to feed 

 on guinea-pigs. By this method he claims that he obtained one 

 positive experiment out of six. In this positive experiment the 

 guinea-pigs developed typical symptoms in about fifteen days. 



Noguchi also cultivated the Leptospira three times directly from 

 yellow fever patients. The medium consisted of a mixture of one 

 part of serum from non-immune persons and three parts of Ringer 's 

 solution, used both in the liquid form and also in the semi-solid 

 condition, by adding small amounts of melted neutral agar. To 

 this about 1 c.c. of citrated blood from the median basilic vein of 

 the patient was added, first being mixed with the semi-solid agar, 

 while this was in the fluid condition at 42 C. This was allowed 

 to solidify by cooling, and the warm Ringer's solution was then 

 poured on the semi-solid portion and about 0.5 to 1 c.c. of the same 

 blood introduced. The culture was then covered with paraffin oil. 



He also cultivated the organisms from infected guinea-pigs. 



He described them as follows: The Leptospira is an extremely 

 delicate filament about 4 to 9 micra in length and 0.2 of a micron 

 in width. It tapers gradually toward the extremities and ends 

 in thick sharp points. It is minutely wound at short and regular 

 intervals, each section measuring about 0.25 of a micron. The 

 windings are so placed as to form a zigzag line at angles of 90. 



It is not visible by ordinary light, but is easily seen with a dark 

 field. It is actively motile, showing a vibratory motion and some- 

 times twisting parts of the filament. It bores into the semi-solid 

 material and is remarkably flexible. 



It is difficult to stain with ordinary dyes, but can be fixed by osmic 

 acid and stained with Giemsa or other polychrome stains. 



In regard to transmission, it is an important fact (Noguchi) 

 that 67 per cent of the wild rats of Guayaquil showed organisms 

 in their kidneys similar in appearance to the leptospira just 

 described; and these inoculated into guinea-pigs produced lesions 

 similar to those produced by the yellow fever blood. 



