LABORATORY AND GREENHOUSE STUDIES, 65 



In agar stabs the surface growth is thin and extends across the tube 

 and sHghtly up the glass. The stab growth is slender and slightly 

 beaded. 



On agar streaks the growth is good, irregular, and bordered by 

 numerous tiny white colonies. 



On gelatin stabs the surface growth is thin and white. The stab 

 growth is slender and bordered by, or consisting of, many tiny, 

 separate, white colonies. 



On gelatin plates the colonies are small, with irregular margins and 

 uneven surface. After several days' growth the colony is ysually 

 zonate with alternating ridges and depressions. Savage ^ studied 

 the appearance of Bacillus coli on gelatin plates and came to the 

 conclusion that while there was a typical form of colony for this 

 organism, yet there was enough variation in the forms to prevent 

 using this character alone in diagnosing the species. Comparison by 

 the writer of B. coli on gelatin plates with the coconut organism 

 shows them to be, for all practical purposes, identical. Usually B. coli 

 assumed the zonate form 24 hours later than the coconut organism 

 under the same conditions, but ultimately they appeared indis- 

 tinguishable. 



GROWTH WITH AND -VmiHOUT AIE. 



The fact that the organism grows in the stab inoculations of agar 

 and gelatin and luxuriantly in the closed ends of fermentation tubes 

 is indicative of its ability to grow either in the entire absence of free 

 oxygen or at least when only very little is present. 



Experiments were made with large U tubes m which pyrogallic 

 acid and caustic soda were placed in a test tube and inserted in one 

 end of the U and a beef-bouillon culture of the organism was placed 

 in the other end. The ends of the U were sealed by standing them 

 in beakers containing glycerin, and in some of the experiments with 

 glycerin in one beaker and mercury in the other. The fluid used in 

 each case, either glycerin or mercury, rose in the tube as the air was 

 exliausted by the union of the pyrogallic acid and the caustic soda, but 

 it was not possible to say that an absolute vacuum, or rather an entii-e 

 absence of oxygen, was obtained. In 24 hours the cultures were 

 always well clouded. Similar experunents were made in which it 

 was contrived to insert also in a U tube a test tube containing bouillon, 

 grape sugar, and methylene blue. In no case did this methylene 

 blue lose its color, as would be expected if there were entire absence 

 of oxygen. Similar experiments were made with large straight test 

 tubes. The seal consisted of a rubber stopper smeared with vaseline. 

 Heavy clouding also took place in these tubes, but the methylene 



1 Savage, W. G. Gelatin Surface Colonies of Bacillus Coli Communis. Journal of Pathology and Bac- 

 teriology, vol. 9, 1903-4, p. 358. 



6389°— Bill. 228—12 5 



