LABORATORY STUDIES 169 



(/() 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-gall bacteria (Pseudomonas tumefaciens} , 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 (Bacterium 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 desirability for the beginner in 

 Botany. 



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



Cambridge, 1904. 

 JOSEPHINE E. TILDEN, The Myxophyceae of North America and 



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



1910. 



G. B. DE TONI, 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. CAMPBELL, A Text-book of General 



Bacteriology, New York, 1910. 



