EXPLANATION OF THE PLATES. 
567 
Fig. 22. 
Pollen of 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 The tube is of extreme tenuity, and may be withdrawn from the 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. S3. 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. 
Fig. 34. Grain of pollen of Datura Stramonium, emitting its tube ; after Bron- 
gniart: a, pollen-tube. 
Fig. 35. Grain of pollen of Ipomtea hederacea, emitting its tube ; after Bron- 
gniart : a, pollen tube. 
Fig. 36. Mode in which the pollen acts upon the stigma in QDnothera biennis : 
a a, pollen tubes ; h h, tissue of the stigma into which these tubes penetrate ; 
after Brongniart, 
Fig. 37. Mode in which the pollen acts upon the stigma in Antirrhinum majus; 
after Brongniart. The pollen sticks to the surface of the stigma, and the tubes 
plunge down between the utricles of cellular tissue, of which the stigma 
consists. 
Fig. 38. A grain of pollen of the same plant with its tube, more highly mag- 
nified : a, the pollen tube. 
PLATE V. 
Fig. 1. Vertical section of the ovarium of Dictamnus albus : a, gynophorus, or 
elongated base of the ovarium; 6, base of the style; c, cavity where the car- 
pella have not united ; d, cell ; e, placenta, with ovula attached to it. 
Fig. 2. Transverse section of the same in a more advanced state, where the car- 
pella are beginning to separate : a a, carpella ; h, an ovulum cut through ; 
c, placenta. 
Fig. 3. Pistillumof Coriaria myrtifolia ; consisting of five carpella, each bearing 
a single linear stigma, and collected round a common elevated axis, the base of 
which is seen at a. 
Fig. 4. Ovarium of Lamium album ; a, base of the style ; h, carpella pressed 
together into a square concave body ; c, fleshy lobed disk. 
Fig. 5. Pistillum of Pinguicula vulgaris : a, ovarium ; b, style ; c, stigma, con- 
sisting of two very unequal lobes. 
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