238 Journal of Agricultural Research voi. iv, N0.3 



at first glance they seem to be completely detached from the cytoplasmic 

 network, but a closer observ^ation shows very feebly staining joining 

 strands. Preparations from liquid cultures also present the same 

 cellular structures. 



CONCLUSIONS 



From the present paper the following conclusions may be drawn : 

 (i) The cells of Azotohacter chroococcum Beij. present a complex nature 

 and different stadia of cytological make-up. Conforming to the con- 

 clusions of Penau (14) on B. anthracis and all endosporous bacteria, 

 A. chroococcum shows an undififerentiated stadium. The nuclear stadium 

 and the sporogenous one were not studied in the present paper. 



(2) The organism with which we are working presents peculiar granu- 

 lations, which seem not to have any relation to the reproduction of the 

 cell. 



(3) These granulations take the basic dyes and are constituted neither 

 of fats nor glycogen, starch nor chromatin. They seem to be of a meta- 

 chromatic nature. 



(4) They seem to have their genesis from the nucleus, since they are 

 always to be found embedded in that part of the protoplasm which 

 shows nuclear characteristics. 



(5) Their disposition in the cells is not regular, but changes in different 

 individuals. 



(6) Their place in Meyer's (12) system is uncertain, since by the present 

 work on their nature they seem to belong to the class of ergastic structures, 

 or stored material, while according to Prazmowsky's (15) work their 

 reproduction might place them in the class which Meyer calls "proto- 

 plastic." Their regular appearance in the cells of A. chroococcum might 

 be caused by the special conditions of life. 



LITERATURE CITED 



(1) ASHBY, S. F. 



1907. Some observations on the assimilation of atmospheric nitrogen by a free 

 living soil organism. — Azotobacter chroococcum of Beijerinck. In 

 Jour. Agr. Sci., v. 2, pt. i, p. 35-51. 



(2) Beijerinck, M. W. 



1901. Ueber oligonitrophile Mikroben. /n Centbl. Bakt. [etc.], Abt. 2, Bd. 7, 



No. 16, p. 561-582, I pi. 



(3) and Delden, A. van. 



1902. Ueber die Assimilation des freien Stickstoffs diu-ch Bakterien. In 



Centbl. Bakt. [etc.], Abt. 2, Bd. 9, No. 1/2, p. 3-43. 



(4) Berthelot, M. p. E. 



1885. Fixation directe de 1 'azote atmospherique libre par certains terrains 

 argileux. /nCompt. Rend. Acad. Sci. [Paris], t. loi.no. 17, p. 775-784. 



(5) Fischer, Hugo. 



1906. Zweiter Beitrag zur Kenntnisder Lebensbindungen von Stickstoff sam- 

 melnden Bakterien. In Centbl. Bakt. [etc.], Abt. 2, Bd. 15, No. 7/8, 

 p. 235-236. 



