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STATE BOARD OF AGRICULTURE 



the host cell. Their length would in most cases prevent their assuming any- 

 other position, although smaller forms are sometimes found in an oblique 

 position. The flagella are extended in the majority of cases but may be 

 coiled in various ways. The full extension of the flagella seems to be corre- 

 lated mostly with the position of the organisms in relation to the host cell 

 nucleus. In nearly every case the flagellates will be found to lie very close 

 to the nucleus with one or both flagella in contact with the nuclear surface, 

 or else the body of the organism is located parallel to the axial line of the 



Fig. 4. Photomicrograph of a single biflagellate organism in a sieve parenchyma cell of bean petiole. 

 X 1800. 



A. Body of the flagellate. 



B. Flagellum. 



C. Sieve parenchyma cell. 



nucleus and one flagellum is coiled around it. In one very interesting case 

 the entire body of the flagellate lay in contact with the nucleus, the flagella 

 being fully extended from both poles. Nuclei in various stages of degenera- 

 tion occur throughout the phloem tissues and there seems httle doubt of the 

 direct influence of the presence of the flagellates upon the activities of this 

 structure. 



The mode of division of the biflagellate forms is by simple, longitudinal 

 binary fission. Preceding the division of the organism the basal granules 

 divide, the flagella split throughout their entire length or divide only par- 

 tialty, a v-shape slit appears in each end of the body and division then oc- 



