558 CONSERVATIVE ORGANS. [LECT. X. 



kinds of vessels described in the former division, 

 which appear as dots in a transverse section of the 

 petiole situated almost close to its external sur- 

 face; or as represented at a. a. a. a. (g.), a highly 

 magnified view of the section. The number of the 

 spiral vessels in each fascicle is generally six, three 

 large and three smaller, symmetrically arranged, as 

 may be seen in a transverse section of one of the 

 fasciculi (10. a.) viewed under the microscope ; and 

 the whole surrounded by a mass of much denser 

 cellular matter than the rest of the substance of 

 the petiole. The returning or proper vessels 

 (10. ft.) are much smaller and more numerous than 

 the spiral; and are congregated into a bundle which 

 occupies a space close to the former, between it 

 and the cuticle, and is bounded by a mass of the 

 same dense cellular matter (10. c.) as that which 



