238 THE INFECTIOUS DISEASES. 



and colon bacilli. This assumption is not wholly justified by the facts, since many of 

 the biological -as well as some of the morphological characters of the two are quite dis- 

 similar. 



The difficulty in distinction is largely limited to the identification of colonies on the 

 common media usually employed in the gelatin and agar plates. Hiss has shown how 

 by a slight modification of the common methods the growth of each form is quite char- 

 acteristic, so much so that pure cultures may be made from the first mixed plates with- 

 out difficulty. 1 When once the two forms are separated, distinguishing characters are 

 readily demonstrable.' 2 



Methods of Staining the Typhoid Bacillus. 



The bacilli from artificial cultures stain readily with the ordinary anilin dyes, such 

 as fuchsin and methyleue blue. In sections, however, they do not stain so readily. 

 They are decolorized by Gram. They may be stained by ZiehVn solution (see p. 223). 

 Stain for half an hour, decolorize in alcohol, clear in oil of cedar, mount in balsam. 

 The decolorization in alcohol should be carefully done to avoid the removal of too 

 much color. Flexner recommends the staining in Loffler's methylene blue solution for 

 two hours; then put in acetic acid solution 1:1, 000 for several minutes; dehydrate in 

 absolute alcohol ; clear and differentiate in oil of cloves ; mount in balsam. The aim in 

 both of these methods is to leave the nuclei faintly colored, but not so much so as to 

 conceal the clusters of more deeply stained bacilli. 



Bibliography of Typhoid. For a resume of the studies on the typhoid bacillus 

 and its relationship to this disease see Xeufeld, Kolle and Wassermann's "Handbuch der 

 Mikroorganismen," Bd. ii., p. 204. For studies on various phases of typhoid infection 

 see Johns Hopkins Hospital Reports, vol. viii., 1900. 



Paratyphoid. 



Recently a group of cases of continued fever has been recognized which give the 

 general clinical picture of typhoid fever, but in which the serum does not agglutinate 

 the typhoid bacillus, and cultures reveal a bacillus in some respects resembling but not 

 identical with the typhoid bacillus, and apparently intermediate between this and the 

 B. coli communis. This bacillus has been called the paratyphoid bacillus, and it is 

 agglutinated by the serum of the cases in which it occurs. The intestinal and other 

 lesions of this disease, which is called paratyphoid, so far as they are known, are not 

 those characteristic of typhoid fever. 3 The limitations of this book do not permit us to 

 enter into detail into the subject of paratyphoid and its bacillus, in which considerable 

 uncertainty still prevails. 4 Regarding the value and significance of the agglutination 

 test the reader should consult works on clinical diagnosis. 



ASIATIC CHOLERA. 



Asiatic cholera is a disease incited by the growth and proliferation in 

 the intestines of a slightly curved or spiral-shaped bacterium, which is 

 called the cholera spirillum Spirillum cholerce Asiaticce (Vibrio cholerse 

 Asiatics). This organism in the early and active stages of the disease 

 may be present in enormous numbers in the contents of the small intes- 

 tine, often penetrating the mucosa. It is usually confined to this situ- 

 ation. Its deleterious effects upon the body appear to be largely due to 

 the production of toxic substances, which in addition to serious intestinal 



1 Hiss, Jour. Exp. Med., vol. ii., p. 677. 1897; Jour. Med. Research., vol. viii., 1902, 

 p. 148 ; also Hiss and Russell, Med. News, February 14th, 1903. 



3 For a study of agglutinativ-e reactions of the colon-typhoid group, see Bruns 

 andKayser, Zeitsch. f. Hyg. u. Infkr., vol. xliii., 1903, p. 401, bibl. 



s See Wells and Scott, Jour, of Infec. Dis., vol. i., 1903, p. 72. 



4 For a resume of this subject, with bibliography, see Libman, Journal of Medical 

 Research, vol. viii., 1902, p. 168. 



