LABORATORY STUDIES 169 



(h) Among the many bacteria of especial interest to us are 

 the following: 



1. Clover-nodule bacteria {Pseudomonas leguminosarum) , 

 which enrich the soil by the production of nitrogen compounds. 



2. Sulphur-bacteria {Beggiatoa alba), which occur as large 

 motile filaments in refrigerator drains. 



3. Apple and pear blight bacteria {Bacillus amylovorus) , 

 causing the blight in apple and pear trees. 



4. Cucumber-wilt bacteria (Bacillus tracheiphilus) , causing 

 the "wilt disease" of cucumbers, and other cucurbits. 



5. Crown-gaU bacteria {Pseudomonas tumefadens) , causing 

 the crown galls in the roots and stems of many plants. 



6. Typhoid fever bacteria {Bacillus typhosus), causing 

 typhoid fever. 



7. Tuberculosis bacteria {Bacterium tuberculosis), causing 

 tuberculosis. 



8. Diphtheria bacteria {Bacterium diphtheriae), causing 

 diphtheria. 



9. Influenza bacteria {Bacteriutn influenzae), causing influ- 

 enza ("Grippe"). 



10. Anthrax bacteria {Bacterium anthracis), causing anthrax. 



11. Cholera bacteria {Microspira comma), causing cholera. 



12. Colon bacteria {Bacillus coli) in the large intestines of 

 most mammals. 



LITERATURE OF MYXOPHYCEAE 



Here as elsewhere only the most necessary works are men- 

 tioned, in the order of their desirabilit}^ for the beginner in 

 Botany. 



G. S. West, A Treatise on the British Freshwater Algae, 



Cambridge, 1904. 

 Josephine E. Tildex, The Myxophyceae of North America and 



Adjacent Regions (Vol. I of jMinnesota Algae), Minneapolis, 



1910. 

 G. B. De Toxi, Sylloge Algarum, Vol. 5, Padua. 

 E. F. Smith, Bacteria in Relation to Plant Diseases, Washington, 



I, 1906; II, 1911. 

 W. D. Frost and E. F. CAiiPBELL, A Text-book of General 



Bacteriology, New York, 1910. 



