STUDIES UPON THE EIFE CYCLES OF THE BACTERIA— 
PART II: LIFE HISTORY OF AZOTOBACTER 1 
By F. Tohnis, Soil Bacteriologist , and N. R. Smith, Assistant Bacteriologist, Bureau 
of Plant Industry, United States Department of Agriculture 2 
INTRODUCTION 
In a preliminary communication, published in this Journal in 1916 (28) , 8 
it was pointed out (1) that the life history of Azotobacter is much more 
complicated than was generally assumed and (2) that the same holds 
true with regard to all other bacteria. The correctness of this general 
statement was further demonstrated by the senior author in a critical 
review of the bacteriological literature, published as Part I of these 
Studies (25). It was shown therein that all findings briefly recorded 
in our preliminary communication are in complete agreement with 
numerous analogous observations made between 1838 and 1918. That 
these older findings had failed to lead to a more accurate knowledge of 
bacterial pleobiosis was caused by their being widely scattered in a 
gigantic literature and by their being not in accordance with time- 
honored, though incorrect, theories concerning bacterial monomorphism 
and constancy. 
Since Part I was written, several contributions have been published 
which further support our standpoint. Bergstrand (4, 5) studied the 
wide pleomorphism of a yellow diphtheroid and advocated that all 
bacteria, on account of their budding, branching, etc. should be classed 
among the Fungi Imperfecti. Brown and Orcutt (7) recorded bacillary, 
fusiform, filamentous branching, diphtheroid, and streptococcoid growth 
of Bacterium pyogenes . Thompson (42) noticed that B. proteus, when 
grown in symbiosis with B. tuberculosis , with other mycobacteria or 
actinomycetes, changed to a diphtheroid, anaerobic organism in 62 per 
cent of all cases. A fuso-spirillary organism was seen by Mellon (31) 
to grow (1) as a yellow actinomyces-like organism, (2) as a diphtheroid, 
making small semitransparent colonies, (3) as a white, aerobic, gelatine 
liquefying coccus, (4) as a typical anaerobic Fusiformis, and (5) as an 
anaerobic spirillum-like organism; filterable gonidia, “giant cocci” 
(evidently gonidangia) and phases of the symplastic stage were also 
recorded. By the same author ( 32 , 33) the “giant cocci” of Coryne- 
bacterium Hodgkinii were isolated and stabilized, and their “ schizogony, ” 
dividing, budding and germination were carefully studied. Wade and 
Manalang (44) made an interesting report upon the various growth 
forms of Bacterium influenzae , wherein they state: 
The familiar bacillus is but a simple form of an organism capable of complex develop¬ 
ment. 
1 Accepted for publication Sept. 26, 1921. 
1 We are indebted to Mr. F. L. Goll, of the Bureau of Plant Industry, for making the photomicrographs 
reproduced on the plates attached to this paper. 
• Reference is made by number (italic) to “ Literature cited,'* p. 430-432. 
Journal of Agricultural Research, 
Washington, D. C. 
acj 
Vol. XXIII, No. 6 
Feb. 10, 1923 
Key No. G-278 
