LECT. VIII.] STRUCTURE OF HERBACEOUS ROOTS. 44l 



general to all herbaceous roots in which the cen- 

 tral part consists of rather more cellular than 

 vascular matter. 



Such is the general structure of herbaceous 

 roots. The main caudex in every instance is more 

 or less of a spindle shape ; but it frequently be- 

 comes forked near the apex, in which case there is 

 a separation of the sap vessels, in the same man- 

 ner as occurs in dividing a skein of threads into 

 two or three parcels; each fork of the root con- 

 taining a portion of the vessels belonging to the 

 main body of the root. In the lateral branches or 

 rootlets, however, this is not the case. These are 

 generally given off at right angles with the main 

 root; and each is composed of one large fasciculus 

 of sap vessels enclosed in a cellular cortex ; but 

 very few of these vessels are given off from those 

 of the caudex; the majority being new vessels ge- 

 nerated in the puncta vitalia; in which the rootlets 

 originate. Whether these new vessels anastomose 

 (using the expression as it is employed in speaking 

 of animal vessels) with the vessels of the main 

 root, I have not yet been able to satisfy myself; 

 they are evidently closely applied to and lost on 

 the surface of the fasciculus of the caudex whence 

 they originate, and pour their contents into it; 

 but this might be effected without an anastomosis, 

 by the lateral transmission through the punctures 

 in the coats of the vessels. 



