IN ORCHIDE^ AND ASCLEPIADEjE. 535 



Tab. 31 (35). Asclepias phytolaccoides. 



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

 coronse and one anthera have been removed. 



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

 membrane formed by the united filaments 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. 



Eg. 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. 



Kg. 4. A longitudinal section of one half of the Stigma and the corres- P36 

 ponding style transversely cut near the base, showing more distinctly the posi- 

 tion of the pollen mass with the protrusion and course of the tubes. 



Fig. 5. The Style of fig. 4, laid open lengthways, exhibiting within its cavity 

 and beyond it the pollen tubes reaching the apex of the placenta, a reflected 

 portion of which, with three of its ovula, is also shown. 



Fig. 6. An impregnated Pistillum, of which the style is laid open longitudi- 

 nally, and the placenta, thickly covered with ovula, exposed, to show the 

 descent and course of the pollen tubes. 



Fig. 7. A Pollen mass, to the apex of which the base of the arm adheres, 

 with pollen tubes protruding from the point of dehiscence : — more highly 

 magnified. 



Fig. 8. A transverse section of a Pollen mass, showing an arrangement of 

 the cells somewhat different from that of A. purpurascens, there being here a 

 middle irregular series, the cells of which in some cases appear to separate and 

 cover the grains after the prodnotion of the tubes. 



Fig. 9. Two grains of pollen with portions of their tubes, very highly 

 magnified, the grain to the left having its outer covering or membrane, which 

 is removed from the grain to the right, and shown separately further to the 

 left. 



Fig. 10. A Pollen mass which has burst and protruded its tubes, exhibited 

 as entering the cavity of the style, which is laid open to show the commence- 

 ment of their descent. 



Fig. 11. Two Pollen masses (with their arms and gland), which have burst 

 and protruded their tubes while still inclosed in the cells of the antheraj ; [737 

 this happening in A. phytolaecoides in that particular kind of decay mentioned 

 in p. 529 of the text. 



Tab. 32 (36). 



Fig. 1. Two Pollen masses of Asclepias purpurascens with protruded tubes ; 

 the only instance met with in which both cords are introduced into the same 

 style. 



