EXPLANATION OF THE PLATES. X15T 



parenchyma of the cortex ; b. b. the divided proper vessels 

 of the cortex ; c. the divided ligneous vessels of the 

 centre. 



PLATE VIII. 



Fig. 1. A. The fibril of a root greatly magnified; a. the vessels id 

 the centre seen through the semitransparent cortex ; b. the 

 natural size of the fibrils : B. transverse section of A. : a. 

 the central vessels ; b. c. the cellular cortex ; d. the section 

 of its natural size. 



2. A. Transverse slice of the stem of Bryonia alba: B. the 



same slice moderately magnified. 



3. Portion of the cuticle of the stem of Bryonia alba greatly 



magnified ; a. a. green, reticulated, lozenge-shape spots on 

 it. 



4. A. Transverse slice of one angle of fig. 2. highly magnified i 



a. a. exterior cortical layer ; b. b. b. b. processes of the green, 

 interior, cortical layer piercing the exterior ; e. e. vascular 

 cortical layer ; d. d. cellular mass of the stem ; /. largest 

 spiral vessel of the vascular fasciculus; g. h. smaller spiral 

 vessels; e. i. entire vessels of the fasciculus (p. 415). B. 

 longitudinal section of A. : the references are the same as 

 the former, (p. 416). 



6. Separated fragments of the vessels, forming the vascular 

 fasciculi in herbaceous stems, highly magnified : a. an an- 

 nular vessel ; b. a spiral vessel ; c. a membranous annu- 

 lated vessel, (p. 417). 



6. A. Transverse slice of the stem of Rubia tinctorum mode- 



rately magnified ; a. the cortex; b. vascular layer; c. cel- 

 lular pulp. B. one corner of the above highly magnified ; 

 a. a. exterior green cortical layer, immediately within the 

 cuticle; b.b. interior green cortical layer; c.c. layer of 

 proper vessels; d. ligneous layer containing the sap or 

 spiral vessels ; e. e. e. cellular pulp. 



7. Portion of a proper or returning vessel, highly magnified. 



8. Portion of a transverse slice of the stem of Hemlock ; . the 



