920 



THE SPIROGH.ETES 



iendency to straighten itself out again. Apart from the primary spirals, which are set 

 more closely than in any other group of spirochsetes, the most characteristic feature of 

 Lepto. iclerohcemorrhagice is its sharp, tapering, hooked ends, which are set at an angle to 

 the main axis, giving the whole organism a resemblance to the letter C or S. During the 

 rotation that occurs when the organism is moving, these hooked ends are whirled round so 

 rapidly that the organism appears to be furnished with a button-hole or an eye-splice at 

 each extremity (Fig. 217). In fluid media the spirochsetes may become entangled with 

 each other and give rise to the characteristic picture of a " nest." This appears as a 

 highly refractile ball composed of hundreds of interlaced organisms, some of which project 

 radially from the circumference (Taylor and Goyle 1931). In dry-fixed films of blood 

 or urine all sorts of forms may be seen, bearing a resemblance to the letters C, S, I, or h. 

 Degeneration forms with thick, blunt, straight ends are not uncommon. According to 

 Kaneko and Okuda (1917), the morphology of the spirochsetes in man is less regular than 

 in the guinea-pig ; they are often shrunken and atrophic, of varying thickness, with greater 

 rigidity and less regular curves ; they may show circumscribed thickenings at two or 

 three points, or they may resemble chains of granules. These irregular forms may perhaps 

 result from the action of immune bodies on the organisms. 



In suitable preparations the spirochsetes may be stained by Giemsa or by one of the 

 silver impregnation methods. In stain'^d films the primary spirals are not visible. Several 

 observers have found that leptospirse may pass through Berkefeld candles (Inada ct al. 

 1916. Bauer 1927, Buchanan 1927, DimitrofF 1927). but the results are variable. Accord- 

 ing to Hiiidle and Elfonl (1933), the organisms are held back by collodion membranes 



having a porosity of 0-25 /j. ; this sug- 

 gests that their diameter is 0-1 /x. 



Cultivation. — Leptospira icterohcemor- 

 rhagicB was first cultivated by the 

 Japanese workers (Inada et al. 1916) in 

 Noguchi's ascitic fluid kidney medium. 

 Subsequently Noguchi (1917) devised 

 other media that were simpler to make 

 and more satisfactory in practice. The 

 first consists of rabbit serum 1 part. 

 Ringer's solution 3 parts, and citrated 

 rabbit plasma 0-5 parts ; the medium 

 should be put up in tubes about |-inch 

 in diameter, and may or may not be 

 covered with liquid paraffin. The second 

 medium is similar to the first, but 0-5- 

 1-0 parts of slightly alkaline 2 per cent, 

 agar are added, at a temperature of 

 60-65° C, the whole medium being well 

 mixed. From this semi-soUd medium 

 the citrated rabbit plasma may be 

 omitted if necessary. The Noguchi- 

 Wenyon medium is likewise satisfactory; 

 it is made by mixing 9 parts of saline with 1 part of 2 per cent, nutrient agar, and 

 adding 20 drops of fresh rabbit's blood to each 10 ml. of the autoclaved medium 

 cooled to 50° C. ; the tubes are not shaken. Very good results are obtained with Fletcher's 

 ( 1928) medium. This is prepared by heating a 12 per cent, solution of rabbit serum in 

 distilled water to 50° C, adding 6 ml. of 2-5 per cent, nutrient agar to every 100 ml. of 

 serum-water mixture, adjusting the reaction to pH 7-4, tubing in 5 ml. quantities, and 

 steriUzing at 56" C. for 1 hour on 2 successive days. According to Gardner (1943rt), the 

 simplest and most satisfactory medium consists of a 12 per cent, solution of heat-inactivated 

 Seitz-filtered rali))it serum in glass-distilled water. For inoculation, 01 ml. of infected 



Fig. 217. — Lepto. icterohwmorrhagice. 



Diagrammatic drawing showing primary and 

 secondary spirals, and hooked and button- 

 hole ends. (After Wenyon.) 



