EXPERIMENT STATION BULLETINS. 



439 



a young organism and it is lying in contact with the host cell nucleus which is 

 destained. Photographed at the same magnification a large individual is 

 shown in Fig. 14. These two organisms illustrate the observed range in size. 

 The figures given in the following table are indicative of the variation found 

 among the organisms but are not to be interpreted as representing conclusive 

 or final sizes of the organisms, for they are not based on measurements 

 of a sufficiently large number of individuals : 



Longest individual measured ..... 28.2 microns. 



Shortest individual measured 6.2 microns. 



Largest individual measured 27 X 6 microns. 



Smallest individual measured 6.2 X 0.5 microns. 



Average all measurements 15.3 X 2.8 microns. 



The total length of these organisms is very difficult to determine because of 



Fig. 14. Very large trypanosome in a sieve tube of mosaic tomato petiole tissue, 

 comparative size with small form in Fig. 12, same magnification. 



X 1500. Note 



the sinuous form of the body. The above measurements were made from 

 one extremity of the body to the other of each individual and no attempt was 

 made to ascertain total length. The sizes are, however, comparative for all 

 types. 



The organs of locomotion have not been determined with certainty. An 

 undulating membrane has been seen faintly stained in some of the forms 

 studied, but no definite posterior or anterior flagellum has been demon- 

 strated. The undulating membrane appears to run nearly the entire length 

 of the body and has only been seen on some of the long, sinuous forms. 

 There is such variation shown by the forms found in the sieve tubes — some 



