A NOTE ON THE MORPHOLOGY OF BACTERIA 



SYMBIOTIC IN THE TISSUES OF HIGHER 



ORGANISMS 



IVAN E. WALLIN 



Department of Anatomy and the Henry S. Denison Research Laboratories, University 



of Colorado, Boulder 



Received for publication January 15, 1922 



In connection with a study of the cytoplasmic relationships 

 of root-nodule bacteria in the common white clover, the author 

 found a stage in the morphogenesis of BacUlus radicicola that, 

 apparently, is not well known. A careful search was made in 

 textbooks of bacteriology for a description or mention of this 

 form, but in vain. Through the courtesy of Dr. F. Lohnis of the 

 United States Department of Agriculture, I have been able to find 

 references to similar forms. Doctor Lohnis (1921) in his exhaus- 

 tive review of the Uterature on the life cycles of the bacteria de- 

 scribes and illustrates round forms of BaciUus radicicola which 

 appear to be similar to the spherical forms that I found. Lohnis 

 and Smith (1916) were the first investigators to observe the spher- 

 ical forms. More recently Bewley and Hutchinson (1920) have 

 observed, apparently, the same form in cultural conditions and 

 call this stage in the morphogenesis of the organism the 

 "swarmer" stage. 



In relation to the spherical forms that have been described by 

 Lohnis (gonidia, regenerative units) it remains to be decided 

 whether the spherical forms that I have called "senile" are 

 derived from the branched forms (bacteroids) or from the 

 sjonplasm. The relationship and character of these spherical 

 forms in the root nodule is decidedly interesting and I believe 

 that a study of these forms in sections of the root nodule may 

 be valuable in the interpretation of their nature. It appears to 

 the author that these spherical forms are fragile and are gener- 

 ally destroyed in the ordinary bacteriological technique. 



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