LABORATOUY AND GREENHOUSE STUDIES. 91 



STODDART'S plate MEDIUiM. 



Stoddart's plate medium is used to distinguish Bacillus coli from 

 Bacillus typhosus. Its value depends upon the fact that a nonmotile 

 or slowly motile organism forms a thick nonspreading or slightly 

 spreading growth on the surface, while a moderately or rapidly motile 

 organism will (luicldy diffuse throughout the medium and over the 

 surface. The efficiency of this medium seems to the writer to be 

 impaired by the fact that not only Bacillus typhosus is rapidly motile 

 but many forms of Bacillus coli are also. For the purpose of com- 

 paring the coconut cultures with those of Bacillus coli, however, the 

 medium may well be of service. 



The composition of the medium was that described in Novy's 

 Bacteriology, page 492. It consisted of gelatin 5 per cent, peptone 

 1 per cent, agar 0.5 per cent, and NaCl 0.5 per cent. The method of 

 using it was to pour into petri dishes and allow it to solidify. The 

 organism to be tested was touched by means of an inoculating needle 

 to the center of the surface of the medium. The Eberth bacilli are 

 said to spread over the entire surface of the plate exposed at 35° C. 

 for 18 hours and to form a transparent, scarcely visible growth. 

 The nonmotile colon bacilli will form a small white colony on the 

 surface without any diffusion. The motile colon bacilli will diffuse, 

 but unlike the Eberth bacilli the growth will be opaque and easily 



visible. 



Stoddart's plates, March 18, 1910, at 22° C. 

 After 18 hours: 



Bacillus coli, and Bacillus coli a: Semiopaque growth over four-fiftha of the 



plate. 

 Coconut 5, 5 a, 3, 3 a: Entirely overgrown with semiopaque growth. 

 Coconut 2, 2 a, 6, and 6 a: Same as B. coli. 

 Coconut 1, 1 a, 4, and 4 a: Nine-tenths overgrown; semiopaque growth. 



The growth in all of these plates was very rapid, semiopaque, and 

 wet shining. There was practically no difference between Bacillus 

 coli and the coconut cultures. Evidently the strain of Bacillus coli 

 here used and the coconut organism are rapidly motile. 



hiss's tube medium. 



Dr. p. H. Hiss has used for differentiating the typhoid bacillus and 

 the colon bacillus a certain "tube medium" and another "plate 

 medium." Only the tube medium ^ has been tried by the writer. 

 It consists of dextrose 1 per cent, beef extract 0.5 per cent, gelatin 

 8 per cent, agar 0.5 per cent, NaCl 0.5 per cent. Ordinary stab 

 cultures are made. The colon bacilU give rise to gas bubbles, 

 whereas the Eberth bacillus does not. 



' Hiss's tube medium. Novy, Frederick G. Laboratory Work In Bacteriology, p. 494. Also Studies 

 from the Department of Pathology of the College of Physicians and Surgeons, Columbia University, 

 New York, vol. 5, 1897-98, pt. 2; and Journal of Medical Research, vol. 8, 1902, pp. 148-167. 



228 



