312 Beer, Development of tlie pollen grain and antlier of some Onagraceae. 
Big. 1. 
Big. 2,3 and 4. 
Big. 5—7. 
Big. 8 and 9. 
Big. 10 and 11. 
Big. 12 and 13. 
Big. 14. 
Big. 15 and 16. 
Big. 17. 
Big. 18. 
Big. 19. 
Big. 20. 
Big. 21 and 22. 
Big. 23. 
Big. 24. 
Big. 25. 
Big. 26. 
Big. 27. 
Big. 28. 
Big. 29. 
Big. 30. 
Big. 31. 
Big. 32—34. 
Big. 35-39. 
Big. 40-42. 
Explanation of Plates 3, 4 and 5. 
Lateral intercellular passage of antlier of 0. biennis in wbicb 
tlie walls bordering upon tlie space have become tbickened and 
cuticularised. Antlier at stage of special-motber-cells. 
Snccessive stages in tbe development of stoma upon antlier of 
0. longiflora. 
Division of pollen-motlier-cell sbowing seven cbromosomes in 
0. longiflora . 
Later stage of division of same. All material from wbicb 
Big. 5—9 were drawn was fixed witli medium chrom-acetic 
mixture. 
Special-motber-cells soon after completion of division. Oenothera 
biennis. 
Special-motber-cells later stage to sbow differentiation of tbe 
first-formed septa from tbe later-formed layers of tbe wall. 
Big. 12 examined in clilor-zinc-iodine solution to wbicb a little 
pliosplioric-iodine solution bad been added. Big. 13 examined 
in corallin soda solution 0 . biennis. 
Bapbide-sac of antlier of 0. biennis. Strong Blemming's sol. 
and Heidenbain's liaematoxylin. 
Young pollen grain of 0. biennis immediatly after formation of 
first pollen-wall strong Blemming’s sol. 
Sliglitly older pollen-grain of 0. biennis. Interstitial bodies 
formed. 
Similar pollen-grain to tliat in Big. 17 but witli two nuclei. 
Pollen grain of 0. biennis measuring 40 g in diameter. Living 
material examined in .6% Ya CI solution. 
Branclied end,of pollen-tube of Epilobium tetragonum. 
Abnormal pollen grains of 0. biennis witb two and one inter¬ 
stitial body respectively. Examined in . 6 % Ya CI solution. 
Pollen grain of 0. biennis 45 g across Blemming's solution 
metbylene blue and fucbsin. 
Pollen grain 0. longiflora 70 g across. Living material exa¬ 
mined in . 75 °/o Ya CI solution. 
Section of pollen grain of 0. biennis measuring about 86 u 
across tbe entne grain to sbow protoplast at end of tbe 
period of secretory activity and wlien it bas expanded until 
it nearlv fills tbe cell-cavitv Blemming's sol. Heidenbain's 
liaematoxybn and bismarck brown. 
Similar pollen grain to Big. 25 nucleus sbowing first stage of 
mitosis. 
Section of pollen grain of 0. biennis measuring about 86 g 
across sbowing vegetative and generative (g) cells. Blemming's 
sol. Heidenliein’s baematoxylin and bismarck brown. 
Pollen grain of 0. biennis measuring 150 g across to sbow 
tbe tliree arms of protoplasm extending to tbe bases of tbe 
tbree interstitial bodies wliere tbe intine was just beginning 
to be formed. Living material examined in . 6 0 o Ya CI 
solution. 
Pollen grain 0. longiflora to sbow tbe tbree arms of cyto- 
plasm. Bixed witb Worcester’s fluid. Metbylene blue and 
fucbsin stain. 
Tapetal cell of 0. longiflora witb 8 nuclei. Strong Blemming 
sol. Metbylene blue and fucbsin preceded by crocein stain. 
Tapetal cell of 0. longiflora witb 6 nuclei. 
Tapetal cells of 0. biennis to sbow direct division of nucleus. 
Strong Blemming's solution. 
Tapetal cells to sbow constricted and irregulär nuclei some 
of wbicb may be stages of direct division to otliers no sucli 
significance attacbes. 
Tapetal cells from somewliat older antbers in wbicb pollen 
grains measure from 60 to 95 g across. To sbow constricted nuclei. 
