THE ANATOMY OF A HYBRID EQUISETUM 
the genus Equisetum, are all points to be cleared up by further in- 
vestigation. 
In conclusion, I wish to express my best thanks to Professor 
Jeffrey for suggestions in regard to this work, and for material of 
E. hiemale and E. variegatum var. Jesupi from Toronto; and also to the 
authorities of the Gray Herbarium of Harvard University for material 
of E. variegatum and E. variegatum var. Jesupi, and for the loan of 
herbarium sheets from which the photographs of plate I were made. 
EXPLANATION OF PLATES V-VIII 
Fig. I. Equisetum variegatum. X i. 
Fig. 2. Same. X 2. 
Fig. 3. E. hiemale. X i. 
Fig. 4, Same. X 2. 
Fig. 5. E, variegatum var. Jesupi. X i. 
Fig. 6. Same. X 2. 
Fig. 7. E. variegatum, transverse section of aerial stem. X 6g.- 
Fig. 8. E. variegatum var. Jesupi, transverse section of aerial stem". X 125. 
Fig. 9. Same. X 30. 
Fig. 10. Same. X 125. 
Fig. II. E. hiemale, transverse section of aerial stem. X 15. 
Fig. 12. Same. X 125. 
Fig. 13. E. variegatum, transverse section of internode of rhizome. X 60. 
Fig. 14. Same, at node. X 60. 
Fig. 15. E. variegatum, var. Jesupi, transverse section of internode of rhizome. 
X 60. 
Fig. 16. Same, at node. X 60. 
Fig. 17. E. hiemale, transverse section of internode of rhizome. X 15. 
Fig. 18. Same, of node. X 15. 
Fig. 19. E. variegatum, longitudinal section of rhizome. X 60. 
Fig. 20. Same, section of sporophore and sporangia. X 60. 
Fig. 21. E. variegatum var. Jesupi, longitudinal section of stem. X 40. 
Fig. 22. Same, section of sporangium. X 250. 
Fig. 23. E. hiemale, longitudinal section of rhizome. X 15. 
Fig. 24. Same, section of sporangia. X 120. 
