8 THE MORPHOLOGY OF BACTERIA 



secretory product and made up of galaktan, a polysaccharide of galactose, and con- 

 tains no protein. The investigations of Toenniessen were later extended by Kramar' 

 who found that the capsule of the Friedlander bacillus consists of galaktan, that of 

 Bacillus anthracis of a glycoprotein, and that of Bacillus radicicola of a dextran. The 

 capsules of different bacteria thus differ among themselves radically in their chemical 

 composition. 



Recently Avery, Heidelberger, and Goebel^ have approached the question of cap- 

 sule formation in bacteria from still another angle. From the pneumococcus type II 

 they have obtained the capsular substance and found it to be a nitrogen-free poly- 

 saccharide. This substance was non-antigenic. From the bacterial cell they obtained 

 a protein substance which was antigenic but had no type specificity. In order to get 

 type-specific reactions in animals it was necessary to employ both the protein con- 

 stituent of the cells and the capsular substance before separation of the cell mass into 

 its constituents. A similar carbohydrate, a nitrogen-free polysaccharide, was obtained 

 from a strain of the Friedlander bacillus. The carbohydrate obtained from the type 

 II pneumococcus was the same as the substance found by Dochez and Avery^ in the 

 blood and urine in pneumococcus infections in man. Julianelle,^ working with rabbits 

 infected with a strain of the Friedlander bacillus, found specific substances in the urine 

 and blood which were practically identical with those in the soluble portion of the or- 

 ganisms. Finally, Smith^ has reported biochemical studies on certain encapsulated 

 strains of Bacillus coli. She states that the capsule materials consist of 80 per cent of a 

 special carbohydrate, a hexose, together with a small amount of glycuronic acid. In 

 order to show that this carbohydrate really represents capsule substance, she employed 

 strains of the encapsulated Bacillus coli deprived of their capsules through mutation 

 cultivation (see Theobald Smith).'' On comparing the filtrates from the two organ- 

 isms, she was able to show that the precipitin test was one hundred times less active 

 specifically with the filtrate from the mutant than with the filtrate from the encapsu- 

 lated strain. These observations on the kinds of substances which may be obtained 

 from capsules are of fundamental importance and must, as they are further amplified, 

 aid materially in the interpretation of the composition and especially the function of 

 capsules.^ 



SPORES 



As already mentioned, the conception of Kruse that spores in the bacteria are 

 resting bodies like the cysts of the protozoa has had wide acceptance. According to 

 this conception, spores are produced under unfavorable conditions, especially as re- 

 gards food supply, serve purely for the perpetuation of the species, and show no evi- 

 dence of vital activity. A number of reports have recently been published which must 

 change our interpretation of spore formation. Thus Ruehle^ has found that spores 



' Kramar, E.: Centralbl. f. BaclerioL, 87, 401. 1922. 



' Avery, O. T., Heidelberger, M., and Goebel, W. F.: /. Exper. Med., 42, 701, 709, 727. 1925. 



3 Dochez, A. R., and Avery, O. T.: ibid., 26, 477. 191 7. 



-I Julianelle, L. A.: ibid., 46, 113. 1926. 



s Smith, D. E.: ibid., p. 155. 1927. 'See chaptet lii in this volume. 



^ Smith, T.: ibid., p. 141. 1927- ' Ruehle, G. L. A.: J. Bad., 8, 487. 1923. 



