NOT DESCRIBED IX PREVIOUS SECTIONS. 569 



sometimes they are united in pairs, but only very rarely do they occur as 

 filaments. The ends are slightly rounded. The bacillus shows moderate 

 motility : Gram's stain is negative. . 



" Growth takes place upon all culture media at the room temperature, 

 but better in the thermostat. Gelatin is not liquefied. The colonies resemble 

 those of B. typhosus, being more nearly like them when first isolated from 

 the dejecta than after a period of cultivation outside the body. After many 

 months of such saprophytic growth the colonies become thicker, exhibit a 

 moist surface, and are less translucent. The strokes upon agar slants show a 

 similar alteration. At first the growth extends but little laterally, but later 

 on it becomes two to three millimetres in width, and generally shows distinct 

 indentations at the edges. Upon gelatin the colonies are more delicate ; the 

 stab extends along the line of puncture only, spreading very little at the sur- 

 face of the medium. 



"On potato, growth takes place along the line of inoculation and spreads 

 beyond. After some days it is a little elevated and of a pale-brown tint. On 

 unfavorable potatoes the growth is slight, moist, and membranous, resem- 

 bling, except for the greater amount of moisture, that of B. typhosus when 

 typical. 



" Sugars glucose, lactose, and saccharose are not fermented gaseously. 

 In glucose media a moderate acid production takes place. 



" Bouillon is clouded diffusely and a sediment forms. There is no pro- 

 duction of a pellicle. 



" Litmus milk assumes, after twenty-four to seventy-two hours, a faint 

 lilac tinge. After the lapse of from six to eight days alkali begins to be pro- 

 duced, which increases in amount until the litmus is rendered deep blue in 

 color. No coagulation of the milk ensues. 



"Indol is not always formed. Even in sugar-free bouillon it may fail to 

 appear, or it may be produced in small quantities only. 



"Suitable cultures of this organism, when tested for the agglutination re- 

 action with the blood serum of persons suffering from dysentery the host of 

 another individual give, in many cases, a positive result. 



"The bacillus is pathogenic for the ordinary laboratory animals. It is 

 abundant in the acute cases in which it may be the predominating organism ; 

 it becomes more difficult to find as the cases progress toward recovery or 

 chronicity. In the ordinary chronic dysentery of Manila, in which amoebae 

 are commonly encountered, it was not found. It can be cultivated from the 

 dejecta during life, and the intestinal contents, mucous membrane, and 

 mesenteric glands in fatal cases. 



"Since the publication of Shiga's studies, Escherich and Celli have both 

 attempted to show that the organisms obtained from their respective epidemics 

 of dysentery are identical with the B. dysenteriae. In both cases they have 

 proceeded upon the false assumption that Shiga's microorganism was a 

 variety of B. coli communis, whereas, in point of fact, it is much more nearly 

 related in its cultural and physiological properties to B. typhosus. 



"The question naturally arises, In what ways does it differ from B. 

 typhosus? Comparison of the Eberth-Gaffky and Shiga bacilli show the 

 criteria of difference to be by no means numerous. The main features, how- 

 ever, are as follows : The latter shows less marked motility when first iso- 

 lated and a tendency to lose motility rapidly in artificial cultivations ; it 

 displays a more uniform generation of indol ; after a brief preliminary acid 

 production in milk it gives rise to a gradually increasing alkalinization ; it is 

 inactive to blood serum from typhoid cases ; but reacts with serum from 

 dysenteric cases to which B. typhosus does not respond. . . . 



' ' Bearing directly upon these considerations are the results of Lieutenant 

 Strong's studies, continued after our departure from Manila. He writes : 

 ' After you left we had a large number of acute cases of dysentery. It seems 

 certain that this form, which we have begun to speak of as acute infectious 

 dysentery, is independent of amcebae. I have now records of fourteen cases 



