OP ARTS AND SCIENCES. 67 



T wish, in conclusion, to express my gratitude to those who have 

 aided me iu my work, and especially to Professor Farlow and to 

 Mr. Holden, to both of whom I am very greatly indebted. 



Cryptogamic Laboratory, 



Harvard University. 



EXPLANATION OF FIGURES. 



Fig. 1. A portion of a plant of Tuomeija Jlaciatilis, Harv., of the natural size, 

 collected at Oxford, Conn., by Mr. Harger, Nov. 9, 1889. 



Fig. 2. A portion of the very tip of a branch, showing the protruding filament 



with the young ramelU at its base. X 500. 

 Fig. 3. The protruding filament with the ranielli removed. X 375 X 2. 

 Fig. 4. Cross-section through the protruding filament about 40 /j. from tip. 



X 375 X 2. 

 Fig. 5. Portion of a young branch, with ramelU removed by crushing, showing 



a young branchlet. X 375 X 2. 

 Fig. 6. Young portion of a branch, showing the axis and two ramelli. Tiie 



other ramelli have been removed by crushing. About .25 mm. from the 



tip. X 375. 

 Fig. 7. A portion of a young branch, showing one ramellus with young 



secondary filaments just starting forth. X 375. 

 Fig. 8. Older specimen, showing the origin of the secondary filaments. X 375. 

 Fig. 9. Older portion, with some of the ramelli removed by crushing, show- 

 ing a more advanced stage of the ramelli and of the secondary filaments. 



X375. 

 Fig. 10. Cross-section of an adult, solid stem. 



a, axial cell. 



b, bundle of secondary filaments. 



c, inner portions of ramelli. 



d, outer " " 



e, coat of monihform filaments. X 312. 

 Fig. 11. Showing an adventitious branch. X 375. 



Fig. 12. Showing a very young procarpic branch. X 500. 

 Fig. 13. Young procarpic branch producing branchlets on the convex side. 

 X500. 



Fig. 14. Young procarpic branch, which has become decidedly spirally twisted. 

 X 500. 



Fig. 15. Procarpic branch with trichogyne {tr.). The branchlets have been 



mostly removed in crushing. X 500. 

 Fig. 16. Showing a trichogyne attached obliquely to the pedicel. X 385. 



