1902] A MORPHOLOGICAL STUDY OF ASCLEPIADACEAE 409 



leaves, in some species also on the midribs of the leaves; they 

 are not in pairs, as stated by Engler and Prantl ; and are not 

 nectariferous. 



5. The tube of the corolla seems to be of toral origin. 



6. The adaxial surface of the corolla becomes papillose at 

 the time of blooming. 



7. The stamens are remarkable in the development of inter- 

 cellular spaces. 



8. The horn and hood are lateral outgrowths from the fila- 

 ment and composed largely of extremely loose tissue. 



9. The fibrovascular bundle of the stamen loops into the 

 hood to near its tip, the curvature beginning after the walls of 

 the tracheids have formed spirals. 



10. The elongation of the bundle to form the loop seems to 

 , take place by the stretching of the old tracheids and the forma- 

 tion of new ones at their sides. 



11. The horn contains no vascular tissue. 



12. The top of the "head/* and not the functional stigma, is 

 believed to be homologous with the stigma of normal angiosperms. 



13. In general Corry's account of the formation of the caudi- 

 cules, or connectors, and corpuscula is corroborated. 



14. The generative cell divides near the tube nucleus, and 

 in the normal manner. The division occurs before the forma- 

 tion of pollen tubes. 



15. The pollen tubes from the same pollinium all enter the 

 same ovary. 



16. When the pollen tube enters the stigma the tube nucleus 

 is behind the male cells, but it is doubtful whether any reported 

 positions of nuclei in pollen tubes are beyond question. 



> 17. The tube nucleus gets no further than the upper part of 



the ovary. 



18. There is a single integument. 



19. The nucellus is a single layer of cells enclosing the 



sporogenous row. 



20. A single hypodermal archesporial cell forms a row of four 

 megaspores without the formation of a parietal cell. Occasion- 

 ally there is more than one archesporial cell. 



