458 R. S. BREED, H. J. CONN AND J. C. BAKER 



Family 5. Bacillaceae. Rods producing endospores, usually 

 Gram-positive. Flagella, when present, peritrichous. Prima- 

 rily saprophytes secreting proteolytic enzymes. A few parasites. 



Appendix. Bacteria Imperfecta. A temporary group to con- 

 tain the non-motile, non-spore-forming rods, whose relationship 

 to any of the above families cannot be shown. 



Order II. Actinomycetales. Cells usually elongated, fre- 

 quently filamentous and with a tendency to the development 

 of branches. 



Family 1 . Mycohacteriaceae. Cells do not form true branched 

 filaments. Frequently show swellings, clubbed or irregular shapes. 

 Gram-positive. Frequently pathogenic. Aerobic. 



Family 2. Actinomycetaceae. True filaments formed, de- 

 veloping into a definite branched mycelium. One-celled re- 

 productive bodies formed by fragmentation. Aerobic and 

 anaerobic. Occasionally pathogenic, but ordinarily living upon 

 simple organic compounds. 



Order III. Thiohacteriales. Cells free or united in elongated 

 filaments. Cells typically containing either granules of free 

 sulphur or bacterio-purpin or both, usually growing best in pres- 

 ence of hydrogen sulphide. 



Order IV. Chlamydohacteriales. Cells normally in elongated 

 filaments. Iron often present. Usually a well-marked sheath. 



Order V. Myxohacteriales. Cells united during the vegetative 

 state into a pseudoplasmodium which passes over into a highly 

 developed cyst-producing resting stage. 



Appendix. Spirochaetaceae. Spirilliform organisms, multiply- 

 ing by transverse division. Frequently parasitic. 



REFERENCES 



Buchanan, R. E. 1915 Nomenclature of the Coccaceae. J. Inf. Dis. 17, 528- 



541. 

 Buchanan, R. E. 1917 Studies in the nomenclature and classification of the 



bacteria. J. Bact, 1, 591-596, 2, 155-164, 347-350. 

 Chamberlin, T. C. 1916 The origin of the earth. Chicago. 

 Chamberlin, T. C. and Chamberlin, R. T. 1908 Early terrestrial conditions 



that may have favored organic synthesis. Science, n. ser. 28, 897-911. 

 Conn, H. J. 1917 Actinomycetes in soil. N. Y. Agr. Exp. Sta., Tech. Bui. 60. 



