862 



Additional Note on the Ovule of Viscum album. 

 By William Wilson, Esq. 



(Continued from vol. ii. p. 986). 



In Dr. Lindley's ' Vegetable Kingdom,' article Loranthaceae, it is 

 stated, "as a most curious phenomenon," that the ovule of Viscum 

 does not appear till three months after the pollen has exercised its 

 influence. In February last, on dissecting some unexpanded flowers, 

 I ascertained that the three claviform sacs (nuclei), represented at 

 fig. 8, p. 985, exist previous to the period of fecundation. On the 

 2nd of March, the flowers having opened, I again examined the 

 ovules, and traced the pollen-tubes very distinctly from the surface of 

 the stigma to the region of the nuclei, but could not find any instance 

 of actual contact. At this period each nucleus appears as a pellucid 

 membranous sac, containing almost unorganized fluid, with faint 

 traces of an embryonary sac at the top, where it is rounded and ob- 

 tuse, and the pollen-tubes themselves are rounded and somewhat 

 swollen at the extremity. At a later period it is probable that the 

 pollen-tubes will be found united to the nuclei. 



William Wilson. 



Warrington, March 8, 1850. 



Note on the Ovary of Cucurbitacea. By William Wilson, Esq. 



Strange as it may at first sight appear to those who have not at- 

 tentively studied the subject, it will be found that Dr. Lindley's view 

 of the placentation of this order is not so correct as the one long since 

 published by Dr. Arnott. That of Dr. Wight is founded on a mis- 

 taken opinion that the stigmas are opposite to the placentae, whereas 

 they are placed opposite to the rays of stigmatic tissue. In fact, the 

 ovary of Cucurbits chiefly differs from that of Begoniads in having the 

 margin of each carpellary leaf still more strongly involute, and its 

 whole substance very tumid and pulpy ; so that the three dissepi- 

 ments, though they really exist, are rendered quite inconspicuous. 

 Hence, the placentas are not truly parietal, although they stand very 

 near to the walls of the ovary in consequence of the inflexion of the 



