494 THE SPIROCHETES 



and many workers have searched for a leptospira in dengue fever. Couvy,' for ex- 

 ample, described a small spirochete with a few spirals, found in the blood of dengue 

 patients during the incubation period. Carbo-Noboa^ has isolated several strains of 

 leptospira from certain cases diagnosed as dengue in Guayaquil and has given them 

 the name Leptospira asthcnalgiae. Studies of the pathogenicity and serological re- 

 actions of these strains have not yet been published. The American workers, Duval 

 and Harris,^ failed to find a leptospira but isolated a filterable, microscopically in- 

 visible virus, pathogenic for guinea pigs. Siler, Hall, and Hitchens^ in the Philippines 

 have so far not been able to find a leptospira in their cases. 



Dengue resembles yellow fever in symptomatology even less than seven-day fever 

 resembles infectious jaundice. The general features of acute febrile infections at their 

 onset are common to all these infections, but the cardinal symptoms of yellow fever — 

 namely, intense and acute nephritis, hemorrhages, and jaundice — are absent from 

 dengue, which is a non-fatal disease. The skin eruptions so constantly observed in 

 dengue are not seen in yellow fever, and there is little or no immunity from dengue, 

 even when the disease is rather severe, while yellow fever confers durable immunity 

 even when mild. The assumption of a close relation between the two diseases does 

 not appear to be well supported by the clinical and immunological data. 



EXPLANATION OF PLATES 

 Plate I 



Fig. I. — Ehrenberg's drawings of S pirochaeta plicalilis. The upper figures were said by him to 

 represent a magnification of 300 times, the lower ones a magnification of 800 times. (From Die 

 Infusionstierchen.) 



Figs. 2. and 3. — S pirochaeta plicatiUs, according to Zuelzer, showing the axial filament; iron- 

 hematoxylin stain. Fig. 2, X 1,100; Fig. 3, X 1,240. 



Fig. 4. — Schaudinn's (see loc. cit.) schematic drawing of a portion of Spirochaeta plicatiUs 



Fig. 5. — A spirochete of the plicatiUs type (5. stenostrepta?) from refrigerator slime. Note the 

 resemblance, except in size, to the organisms drawn by Ehrenberg (Fig. i); darkfield view of fresh 

 preparation. X 1,000. 



Figs. 6-7. — Water forms, similar to that shown in Fig. 5. Fig. 6 shows also a water leptospira; 

 darkfield view. X 1,000. 



Figs. 8-10. — Stained preparations of the Spirochaeta shown in Figs. 5-7. Figs. 8 and 9, prepara- 

 tions fixed in osmic acid and stained with Giemsa's solution; Fig. 10, preparation fixed in Schaudinn's 

 fluid and stained with iron-hematoxylin. X 1,000. 



Plate II 



Figs. 11-18. — Drawings showing the types of flagella of various bacteria as brought out by the 

 Zettnow-Fontana stain. Fig. i\, B. letani, type IV; Fig. 12, B. tetani, type III; Fig. 13, E. typhi; 

 Fig. 14, B. pyocyaneiis; Fig. 15, A. bronchisepticus; Fig. 16, V. metscJmikoin; Figs. 17-18, B. bacilU- 

 formis. 



Figs. 19-21. — Schematic drawing of Cristispira, showing the structure and disposition of the 

 membrane or crista, as brought out by darkfield observations of the course of degeneration. 



' Couvy, L.: Bull. Sec. path, e.xot., 14, 19S. 1921. 



' Carbo-Noboa, J. M.: An. de Soc. med.-quir. del Giiayas, 4, 326. Guayaquil, 1924. 



i Duval, C. W., and Harris, W. H.: J. Expcr. Med., 40, 817, 835. 1924. 



^ Siler, J. F., Hall, M. W., and Hitchens, A. P.: Dengue, Its History, Epidemiology, Mechanism 

 of Transmission, Etiology, Clinical Manifestations, Immunity, and Prevention. Manila: Bureau of 

 I'rinting, 1926. 



