Jan. 7-Mar. 25, 1918 IllustratlOnS IX 



Plate E. i. — A slightly more advanced stage of the condition shown in Page 

 Plate D, figure 16. 2. — An early stage in the abortion of a full-grown i- 

 nulceate microspore. 3. — An early stage of abortion directly following 

 microspore division. 4. — A full-grown i-nucleate microspore containing 

 ver)' scant light-staining cytoplasm; from an anther containing i- and 

 2-nucleate microspores. 5. — Another type of degeneration of a full-grown 

 i-nucleate microspore. 6. — An aborted microspore found among i- and 

 2-nucleate m.icrospores. 7. — A later stage of the type of degeneration shown 

 in Plate D, figure 13; from an anther containing microspores of the stage of 

 development shown by Plate C, figure 15. 8. — Degeneration of the gen- 

 erative cell shortly after division. 9, 10. — Common types of aborted 

 microspores found with mature pollen. 11. — An aborted microspore, of 

 the same type as that shown in figure 7. 12. — A pollen grain showing 

 abortion of the generative cell and an abnormal vacuolate condition of the 

 cytoplasm. 13. — A later stage of the type of degeneration shown in 

 figure 8 670 



Plate 35. A. — Tertiary flower of the pistillate variety, Minnesota ioi7XPro- 

 gressive— 13-40, showing prominent staminodia. B, C. — Primary and 

 secondary flowers of the perfect variety, Minnesota 1017X Progressive— 

 9-24; B showing intermediate and C perfect anthers. D, E, F. — Two 

 primary and a secondary flower of the perfect variety, Minnesota 1017X 

 Progressive — 2-55, showing pistillate, intermediate, and perfect types of 

 flowers. G, H, I, J. — Flowers from the perfect variety, Minnesota 1017X 

 Progressive— 32-1 670 



Plate 36. A, B, C, D. — Cross sections of two loculi of staminodia of the pistil- 

 late varieties. Crescent, Columbia, Minnesota ioi7XProgressive— 11-59, 

 and Seedling 140, respectively. E. — Degeneration of the tetrads in an inter- 

 mediate anther of Fragaria virginiana. F, G. — Later stages of the con- 

 dition shown in figure E. H. — A portion of an intermediate anther from 

 the first flower of Minnesota 3 670 



Effects of Mistletoe on Young Conifers 



Plate 37. A. — Pseudotsuga taxifolia infected with Razoumofskya douglasii. 

 B. — Effect of an inoculation with Razoumofskya campylopoda on the height 

 growth of 6-year-old Pintis jeffreyi 718 



38327°— 19 2 



