EXPLANATION OF THE PLATES. 
557 
Fig. 9. Stamen of Humirium floribundum, after Von Martins ; a, a large tu- 
berculated petaloid connectivum. 
Fig. 10. Stamen of a species of Cryptocarya, from Chili, in which the anther 
opens, as in other Laurineat;, by valves that roll back when they separate ; 
a, one lobe of the anther, with the valve not separated ; b, the other lobe, with 
the valve in the act of rolling back ; c c, abortive stamens under the form of 
glands. 
Fig' 1 1 . Stamen of Berberis vulgaris, exhibiting the same phenomenon ; a, valve 
closed ; b, valve separated and recurved. 
JU the following figures of pollen are taken, with scarcely any alterationt 
from Purkinje, and are draivn to the same scale., so that their relative sizes 
are known. 
Fig. 12. Pollen of Stratiotes aloides. 
13. 
Calla a;thiopica. 
14. 
Elymus sabulosus. 
15. 
Avena latifolia. 
16. 
Scirpus romanus. 
17. 
Pancratium declinatum. 
18. 
Populus alba. 
19. 
Mirabilis Jalapa. 
20. 
Urtica dioica. 
21. 
Armeria fasciculata, 
22. 
Plumbago rosea. 
23. 
Cineraria maritima. 
24. 
Salvia interrupta. 
25. 
Stachytarpheta mutabilis. 
26. 
Polygala spinosa. 
27. 
Heracleum sibiricum. 
28. 
Acacia lophantha. 
29. 
Iresine diffusa. 
30. 
Fuchsia coccinea. 
31. 
Scorzonera radiata. 
Fig. 32. Grains of pollen of Gesneria bulbosa emitting their tubes ; magnified 
180 times. The tube is of extreme tenuity, and may be withdrawn from the 
stigmatic tissue with great facility. Masses of granular matter may be seen 
descending the tubes at irregular intervals. 
Fig. 33. A grain of pollen of the same plant, with its tube magnified 500 times: 
this shows that the tube is an extension of the outer membrane of the grain of 
pollen, if the latter was coated by more than one. The granular matter is 
seen passing down the tubes, and quitting the grain of pollen, which finally 
becomes a transparent empty vesicle. 
l^ig. 34. Grain of pollen of Datura stramonium, emitting its tube ; after Bron- 
gniart; a, pollen-tube. 
Fig. 35. Grain of pollen of Ipomaea hederacea, emitting its tube j after Bron- 
gniart ; a, pollen-tube. 
