420 Mr. Bowman on the Lathraa Squamaria, 3fC. 



Fig. 3. Transverse section of a tuber and its vessels. 



4. Perpendicular section of a tuber at an early stage of its 



attachment to the bark, a, b, c, d. The bark, albur- 

 num, solid wood, and pith of the tree-root. — Fig. 1. 

 2. 3. & 4. are all highly magnified. 



5. Transverse section of the cavity formed in the root of 



the Ash under an old decayed tuber, with the sur- 

 sounding border of the new liber to check the pro- 

 gress of the injury : — highly magnified. 



6. Exterior surface of a subterranean leaf. The dotted 



line a, b indicates the direction of the inclosed space 

 which communicates with the interior chambers. 



7. Perpendicular section of ditto, and one of its chambers. 



8. Transverse section of ditto passing through its imbedded 



chambers. — Fig. 6. 7. & 8. are equally magnified. 



9. The lower portion of Fig. 7- enlarged ad libitum, to 



show the passage by which air is admitted into the 

 cells of the leaf, in the direction of a, b. b. Is the 

 space inclosed by the incurvation of the base of the 

 leaf, d; and c. The orifice into the cell, /. e. The 

 leafstalk. 



10. Transverse section of a leaf, more highly magnified than 



Fig. 8, showing its cellular texture, and the convolu- 

 tions of the chambers, with their papillae. 



11. One of the chambers of ditto, still more highly magni* 



fied, to show more distinctly the papillae scattered over 

 its inner surface. 



12. a,b,c. The papillae very highly magnified. </,&e. Per- 



pendicular and transverse sections of ditto, showing 

 their valves and interior cells. 



13. Minute pear-shaped bladders lodged within the cavities 



of the cellular substance of the leaf. 



XXI. On 



