THE GENUS EQUISETUM. 189 



Explanation of Plates. 



PLATE 26. 



Fig. I. Young archegoniuin of Equisetum hiemale. 

 Fig. 2. Older archegoniuin of E. hiemale. 

 Fig. 3. Older arcliegonium of E. hiemale. 

 Fig. 4. Nearly ripe arcliegonium of E. hiemale. 

 Fig. 5. Nearly ripe arcliegonium of E. anense. 

 Fig. 6. Young embryo of E. hiemale. 

 Fig. 7. Older embryo of E. hiemale. 

 Fig. 8. Still further advanced embryo of E. hiemale. 

 Fig. 9. Young .sporophyte of E. hiemale. 

 Fig. 10. Older sporophyte of the same specie.?. 

 Fig. U. Advanced sporophyte of £. AieHWie. 

 Fig. 12. Young sporophyte of E. limosum. 

 Fig. 13. Older sporophyte of the same species. 



Fig. 14. Diagram showing the relation of the leaf-trace to the nodal wood in E. hiemale. ii. ty. nodal wood; e. eiido. 

 dermis; p. t. protoxyleni ; I. t. leaf-trace. 



Fig. 15. Diagram of the node of Archaeocalamites. I. leaf-traces; b. branches. 



Fig. 16. Diagi'am of the node of Equisetum. I. leaf-trace? ; b. branches. 



Fig. 17. Siu-face of a Calamlte showing the scars of leaves, branches, and root. For ex][)lanatioii see page 181. 



PLATE 27. 



Fig. 1. Stele of Selaginella laevigata showing the origin of a branch. X2.5. 



Fig. 2. Stele of the same species below the point of origin of a branch. X25. 



Fig. 3. Stele of iepidodeJitiron ter-coMrtu at the point of origin of a brancli. X2&. See page 161. 



Fig. 4. Tangential view of the bundles at the node of a Calamite, copied from Williamson. Sec page 163. 



Fig. 5. Tangential view of the bundles at the node of a Calamite, copied from another of Williamson's figures. See 

 page 163. ^ 



Fig. G. Tangential view of /he bundles at the node of a Calamite, copied from a figure of Williamson and Scott. See 

 page 164. 



PLATE 28. 



Fig. 1. Tangential view of (he bundles at the node of a Calamite, copied from Renault. See page 165. (In this figure 

 there are leaf traces,/, only at alternate strands, a sftite of affairs not uncommon in the Calamites). 



Fig. 2. Transverse section of a young trifascicular stem of Equisetum limosum. X200. 



Fig. 3. Transverse .section of the stem of E. hiemale in the nodal region, a. branch ; b. a root. X25. 



Fig. 4. Nodal organ of E. hiemale. X200. 



Fig. 5. Transverse section through the node of E. silvaticum.. a. nodal organs; b. roots ; c. a branch ; d. leaf-traces ; 

 X25. 



Fig. 6. Node of E. anense. c. branches ; d. leaf-traces. x25. 



