390 ACTINOMYCETES. 



of literature up to 1894 is found in the thorough work of Escherich: 

 Aetiologie und Pathogenese der epidemischen Diphtherie, Wien, 1894. 

 Latest literature: Heinersdorff, Arch. f. Ophth., Bd. 46, p. 1. Espe- 

 cially important also are: Neisser (Z. H. xxiv, 443) and Kurth (Z. 

 H. xxvni, 409). C. Frankel(Berl. klin. Wochenschr., 1897, 1085). 

 Zupnik, I. c. 



Microscopic Appearance. — Slender, rather long, rods, 

 often a little bent and usually somewhat swollen at one or 

 both ends. Many times they are arranged in pairs. With 

 Escherich, the following forms may be distinguished: 



1. Wedge-shaped rods, about 1.5-2 y. long, about 

 0.5 fi thick (60, n, iv). 



2. Long cylindric rods (especially upon agar and po- 

 tato) (60, i), 3-4 fi long, 0.4-0.5 ^ thick. 



3. Rods with clubbed swellings (especially upon serum), 

 as much as 6-8 /j. long. The clubs reach a diameter of 

 1.0 At (60, m). 



In 1 and 3 the thin ends are often long and drawn out 

 to a point. The same culture upon alkaline bouillon forms 

 long clubbed rods; upon acid bouillon forms short, wedge- 

 shaped rods. The short forms are more often parallel in 

 arrangement; the long, more at angles, and arranged in 

 rosettes like fingers, etc. 



According to Kurth, the probability of the form under 

 observation being pathogenic is increased if it can be 

 established that in contact preparations, from young cul- 

 tures (six hours at 35°) on LofBer's serum, there are 

 present at least a number of longer forms (seven times as 

 long as thick) or V-shaped forms. Further, Kurth 

 attaches value to an appearance of the young rods being 

 so arranged as to suggest the fingers of two hands, spread 

 out upon each other. 



They have recently been often observed to grow into 

 unbranched threads (in part with clubbed swelling at the 

 ends), and even into branched threads (Babes, Klein, C. 

 Frankel, C. B. xvn, 896). We have also possessed cul- 

 tures which presented striking branching forms in pre- 



Bouillon is first rendered diffusely cloudy, then becomes clear beneath 

 the pellicle. 



Slawyk and Manicantide found thirty completely investigated 

 pathogenic cultures to correspond to the plan, only many of them 

 presented more of the smaller, glistening, elevated agar colonies 



