HERPETOMONAS ELMASSIANI. 



325 



It is well to bear in mind that there is another type of latex 

 system among plants, in which the original cells fuse together by 

 the destruction of their partitions and cross-walls. The result 



FIG. i. Diagrammatic representation of a portion of a simple latex duct such 

 as is found in the species of the genus Asdepias. The latex is secreted by the wall 

 of cytoplasm into the extensive central vacuole. Such a duct will not fuse wiuj 

 others in the course of its growth. 



of the process is the formation of interlacing vessels, in which 

 the latex is. contained. This type of latex systern is found in 

 sucfr plants as lettuce. 



Diagrams representing these two types of latex ducts are 

 shown in Figs. I and 2. 



FIG. 2. Diagrammatic representation of a system of latex vessels such as is 

 found in lettuce. The original cells fuse together to form a network, instead of 

 remaining as independent latex ducts. The type of latex cell involved in proto- 

 zoological studies has been that shown in Fig. i. 



The flagellates known to inhabit the latex systems of plants 

 are probably all insect parasites. They enter the cells of the 



