PLATE XXV. 

 FIG. 1. COLON BACILLUS. 



From a culture in a simple aqueous solutiou of Peptone, 24 hours' growth, incubated 

 tit 37 G. 



The figure is introduced to show the "end-staining" often observed in bacilli, the 

 causation of which is not fully understood. The interest attaching to the present 

 specimen, is that it demonstrates the effect of one particular factor in leading to this 

 result. It has been noticed by Mr. H. C. Haslam that the "end-staining" occurs 

 regularly in the colon bacillus if it is grown in alkaline media. 



In an unstained hanging drop corresponding appearances present themselves, the 

 ends of the bacilli being darker and more granular than the centres. 



FIG. 2. COLON BACILLUS. 



From an agar culture of 48 hours' growth, incubated at 37 C. 



Showing the usual form of the Colon Bacillus : plump straight rods with rounded 

 ends, variable in length and thickness, the shortest appealing as oval. Parallel 

 grouping occurs. As there are many varieties of Colon Bacillus, it is necessary to take 

 one as a standard ; that selected is from a culture of Professor Bscherich's (the 

 original describer of the bacillus). A subculture of this particular organism was 

 obtained from Professor Bscherich by Mr. Wallis Stoddart, to whom the author is 

 indebted for a sample of the strain. 



