EXPERIMENT STATION BULLETINS. 



443 



shown in Fig. 17, while a shorter, broader and more sinuous form is seen in 

 Fig. 18. Some of the forms observed are very long and narrow, being less 

 than 1 micron in width. These very slender forms can undoubtedly pass 

 through the sieve plate perforations, although none have been seen in this 

 position. 



These organisms appear to possess a distinct undulating membrane, and 

 occasionally an individual has been seen with one end of the body drawn out 

 into a rather long flagellum. The membrane is not clearly visible the entire 

 length of the body so that the point of attachment has not yet been ob- 

 served. Dark staining granules, very distinct, are located at each end of the 

 body. They are probably blepharoplasts and it seems probable that an undu- 



FiG. 18. Photomicrograph of a shorter type of trypanosome found in sieve tubes of leaf-roll potato 

 plants. Note that there appears to be a membrane visible on the right side of the body 

 X 1500. 



A. Trypanosome. 



B. Sieve tube. 



C. Sieve tube nucleus. 



lating membrane runs the entire length of the organism. However, since 

 imagination maj^ easily outrun perception in matters of detail, structural 

 characters will require further study. Extreme cases of body sinuosity 

 are common among these organisms and it is in these individuals that an 

 undulating membrane is most often seen. Some details observed in slides 

 studied include: deep-staining granules in various parts of the organisms; 

 the presence of vacuoles; variation in intensity of staining of various parts of 

 the body, in some cases giving a banded appearance to the flagellate. This 

 is seen in Fig. 16. A centrally located nucleus ^^has not been constantly 

 found in the j, flagellates examined. For a study _^of nuclear details other 

 stains will have to be used. 



