627 



pollen-tubes are produced.* When the pollen-grains are immersed in 

 water, they speedily burst and discharge the fovilla from their sides. 

 At fig. 5 {p. 625) is shown a longitudinal section of the pistillum, with 

 one of the ovules at the base of the ovarium. It will be seen that the 

 .stigmatic surface is continued into the cavity of the ovarium, on that 

 side which is most swollen. 



In this plant the elastic valve of the anther fulfils an important func- 

 tion, which seems to have been overlooked. The stamen is not hap- 

 pily represented in Lindley's 'Introduction,' ed. 2, pi. 4, fig. 11. It is 

 placed behind the filament, and is lower than the stigma ; but the 

 valve, on turning up, also twists round towards the stigma, its cavity 

 being filled with nearly all the pollen, which is thus brought to a le- 

 vel with the stigma, ready to be applied to its surface the instant that 

 the filament is excited below. W. Wilson. 



Warrington, May 31, 1843. 



Art, CLI. — A History of the Brilislt Equlscta. By Edward 

 Newman. (Continued from p. 5i)4). 



Equisetum palustre, var. nudum, (Gibson, MSS.) 



This form of the plant is widely but sparingly distributed. I am 

 indebted to Miss Griffiths for specimens from Braunton Burroughs in 

 Devonshire, to Dr. Greville for others from the sands of Barry, and to 

 Mr. S. Gibson for the loan of others from Aldingham, Yorkshire, and 

 Broadbank, Lancashire ; to these Mr. Gibson has attached the MS. 

 name of " var, nudumr 



This plant, as will be seen from the figure (p. 628), differs princi- 

 pally from the normal form in being without branches, or nearly so, 

 the occurrence of a few scattered ones being occasional only, and con- 

 stituting the exception rather than the rule. 1 can scarcely wonder 

 that botanists should have referred such a j^lant to the preceding ra- 

 ther than the present species : this is the case in all the herbaria I 

 have examined, excepting Mr. Gibson's, which came into my hands 

 just as the present paper was going to press, but in time to incorpo- 

 rate a notice of it, and adopt the proposed name. 



* On further examination it appears that the pollen- j^iuins do produce tubes ; and 

 that the stigmatic fluid is of a resinous nature, and does not mix with water. — W. W 

 June 10. 1843. 



3 I 3 



