312 ßeei\ Development of the polleii grain and antlier of some Onagraceae. 

 Kxplaiiatioii of IMatcs Jj, 4 aii<l 5. 



Fig. 1. Lateral intercr 1 1 u 1 a r iiassu^c ol' aiitlier of O. biennis in wliicli 



the walls borderiiig upon the Space have become thickened and 

 cnticularised. Anthei* at stage of special-mother-cells. 



Fig. 2, 3 and 4. Successive stages in the development of stoma upon anther of 

 0. loxijifhra. 



Fig. 5 — 7. Division of poUen-motliei'-cell showing seven chromosomes in 

 0. lonyiflora. 



Fig. 8 and 9. Later stage of division of same. All niaterial from which 

 Fig. 5 — were drawn was llxed with medium chrom-acetic 

 mixture. 



Fig. 10 and 11. Special-mother-cells soon after completion of division. OenotJiera 

 biennis. 



Fig. 12andl3. Special-mother-cells later stage to show differentiation of the 

 tirst-formed septa from the later-formed layers of the wall. 

 Fig. 12 examined in chlor-zinc-iodine Solution to which a little 

 pliosphoric-iodine Solution had been added. Fig. 18 examined 

 in corallin soda Solution 0. biennis. 



Fig. 14. Raphide-sac of anther of 0. biennis. Strong Flemming's sol. 



and Heidenhain's haematoxylin. 



Fig. 15 and 16. Young poUen grain of 0. biennis immediatlj' after formation of 

 first pollen-wall strong Flemming's sol. 



Fig. 17. Slightlj^ older poUen-grain of 0. biennis. Interstitial bodies 



formed. 



Fig. 18. Similar pollen-grain to that in Fig. 17 but with two nuclei. 



Fig. 19. Pollen grain of 0. biennis measuring 40 fi in diameter. Living 



material examined in .6 o/o Na Cl Solution. 



Fig. 20. Branched end of pollen-tube of Epilobium tetragonum. 



Fig. 21 and 22. Abnormal pollen grains of 0. biennis with two and one inter- 

 stitial body respectively. Examined in . 6 % Na Cl Solution. 



Fig. 23. Pollen gi-ain of 0. biennis 45 u across Flemming's Solution 



methylene blue and fuehsin. 



Fig. 24. Pollen grain 0. longiflora 70 u across. Living material exa- 



mined in . 75 o/o Na Ol Solution. , 



Fig. 25. Section of pollen grain of 0. biennis measuriug about 86 fi 



across the entire gTain to show protojilast at end of the 

 period of secretory activitj^ and when it has expanded until 

 it nearly fills the cell-cavitv Flemming's sol. Heidenhain's 

 haematoxylin and bismarck brown. 



Fig. 26. Similar pollen grain to Fig. 25 nucleus showing first stage of 



mitosis. 



Fig. 27. Section of pollen grain of 0. biennis measuring about 86 u 



across showing vegetative and generative (g) cells. Fl emming's 

 sol. Heidenhein's haematoxylin and bismarck brown. 



Fig. 28. Pollen grain of 0. biennis measuring 150 fi across to show 



the three arms of protoplasm extending to the bases of the 

 three interstitial bodies wabere the intine was just beginning 

 to be formed. Living material examined in . 6 o/(^ Na Cl 

 Solution. 



Fig. 29. Pollen grain 0. longiflora to show the three amis of cyto- 



plasm. Fixed with Worcester's fluid. Methylene blue and 

 fuehsin stain. 



Fig. 30. Tapetal cell of 0. /o»^///orö with 8 nuclei. Strong Fl emming 



sol. Methylene blue and fuehsin preceded by crocein stain. 



Fig. 31. Tapetal cell of O. longi/lorci with 6 nuclei. 



Fig. 32 — 34. Tapetal cells of 0. biennis to sliow direct division of nucleus. 

 Strong Flemming's Solution. 



Fig. 35 — 39. Tapetal cells to show constricted and irreg-ular nuclei some 

 of which may be stages of direct division to others no such 

 significance attaches. 



Fig. 40 — 42. Tapetal cells from somewhat older anthers in wliich pollen 

 grains measure from 60 to 95 ^ across. To show constricted nuclei. 



