Fecundation in Orchidea and Asclepiadece. 735 



Fig. 9- A pollen mass after bursting, with its cord formed of 

 the pollen tubes, entering the apex of the style, which 

 . ' is there lacerated. 



10. The two Ovaria with their styles, one being somewhat 



enlarged in consequence of impregnation, and opened 

 longitudinally ; exhibiting pollen tubes extending from 

 the apex of the style to the commencement of the pla- 

 centa, r 



11. The same two ovaria and styles, both opened, to show 



that in one (the left), which is somewhat smaller, 

 no pollen tubes are contained ; the other (the right), 

 which is impregnated, shows the tubes reaching the 

 ovula, but not extending further. 



12. Two grains of pollen (or rather grains deprived of their 



outer membranes,) with portions of their tubes and 

 contained spheroidal granules; proving that the tubes 

 are extensions of this (the inner) membrane : — very 

 highly magnified. 



Tab. 35. Asclepias phytolaccoides. 



Fig. 1. An expanded flower (magnified), from which two of the 

 foliola corona; and one anthera have been removed. 



2. The complete Pistillum, and on one side two of the 



antherae, the membrane formed by the united fila- 

 ments being cut off a little below the stigma ; on the 

 other side, a naked pollen mass applied to the stigma, 

 with its gland and arm adhering. 



3. A longitudinal section of fig. 2, to show on the left side 



a pollen mass, with a small portion only of the arm 

 adhering, applied to the base of the stigma, and which, 

 having burst, shows the protrusion of the cord formed 

 by the pollen tubes, 

 vol,. XVI. 5 b Fig. 4. 



