HERPETOMONAS ELMASSIANI. 327 



numbers of organisms, yet when a droplet was taken for exami- 

 nation as much latex must have been contributed by uninfected 

 cells as by infected. In the cells containing the organisms the 

 concentration was so great that a moderate dilution was entirely 

 ineffective in changing the appearance of the drop as stained 

 for examination. 



Since the plants above mentioned seemed when in the field to 

 have systemic infections in that the slightest wound in any 

 portion of the leaves or stems gave infected latex, and yet the 

 microscopic examination of sections showed but a few of the 

 cells infected, it is evident that the whole plants were penetrated 

 by a relatively few single cells, and that if each individual latex 

 cell fell short of extending completely throughout its plant, it 

 still must have achieved very nearly this remarkable feat. This 

 type of cell attains a notable total size and contains tremendous 

 numbers of nuclei. Its latex-containing vacuole also is probably 

 nearly if not quite the largest of cell vacuoles, making up in 

 length far more than it lacks in breadth. 



CONFINEMENT TO LATEX CELLS. 



Careful study failed to show any flagellates in the plant tissues 

 outside the vacuoles of the latex cells. In some sections there 

 were indeed abnormal and deceptive appearances caused by the 

 flow of latex by capillary action along the conducting tissues. 

 When pieces were cut to be fixed, latex always flowed out over 

 the wounded surfaces. Since the turgidity of the plant was in 

 part relieved by this loss, other specialized cells such as the spiral 

 vessels were invaded by currents of latex along with which the 

 flagellates themselves were carried. The abnormality of this 

 process was made evident by examining the invaded ducts 

 throughout their entire length. The flagellates were seen to be 

 present only near the cut surfaces and to become less and less 

 crowded as the distance from the exterior increased. The tissues 

 in the interior presented a truer picture of conditions in the 

 living plant. 



Since the flagellates were normally confined to the latex cells, 

 and indeed to the latex filling the long vacuoles, it became evident 

 that certain observations made in the field were of more signifi- 



