110 JOURNAL OF THE 



tangential direction; c represents cells of vascnlar tissne which 

 are turned in a tano^ential direction around the cavitv of a cvst 

 which is just below and was removed in making the section; d 

 also represents cells of vascular tissue turned out of their normal 

 course bv the near presence of a cyst. At a is a cyst located in 

 the edge of the vascular tissue of the central cylinder bordering 

 on parenchymatous tissue; behind the cvst the cells of the vas- 

 cular tissue are turned tangentially, and this part of the bundle 

 reaches over outside of the parenchymatous tissue bordering the 

 liber fascicle e. The parenchyma cells between the cyst and the 

 liber fascicle e are elongated radially instead of having their tan- 

 gential diameter the longer. 



In Plate VI, Figs. 36 and 37 represent the structural charac- 

 ter of the galls on tomato roots. The cysts a and b are seated 

 in the parenchyma, the cells of which have long radial diame- 

 ters and converge around the cyst. The parenchyma cells in 

 this section, in a peripheral plane, are longer radially than tan- 

 gentially. At c is represented a dead cyst, probably not impreg- 

 nated, which lies in the woody tissue of the central cylinder. 

 The pitted ducts can be seen to lie radially or perpendicular 

 to the axis, turned from their normal longitudinal direction. 

 Behind the cyst by turning in a tangential direction they con- 

 verge from either side and meet. 



Fig. 37 represents a section through a mature cyst lying in the 

 vascular tissue : the cavity of the cyst at a is filled with eggs and 

 young larvie. At b are represented the vascular cells, which lie in 

 a normal direction, cut transversely. On either radial side the 

 ducts curve around, closely following the contour of the sides of 

 the cavity. At c, the outer tangential side of the cyst cavity, the 

 ducts from both sides and from below converge and meet. 



Fig. 36 represents a section from a moderately sized young 

 gall. In older ones, where the cysts are numerous, there is often 

 presented an intricate maze of these pitted ducts coursing in all 

 directions. 



In potato tubers the parenchyma cells are elongated so that 

 their longer diameter is perpendicular to the surface at that point 



