supersede any farther description of the singular structure of this genus; on which, however, it appears necessary to subjoin a few remarks.
Admitting the parts of fructification to be accurately described, it is not easy to understand in what manner the male influence is communicated to the female organ. In one instance the turbid fluid, which usually fills the cavity of the lower cell of the supposed male organ, was found converted into a powder, and it is not improbable that this change ultimately takes place in all cases where the organ attains perfection. This powder may be supposed either to be discharged by the lateral rupture of the double coat of the containing cell, or a communication may at length be opened between this cell and the tubular axis of the upper cell, which, after the separation of its outer membrane, is open at the top; in this case the ejection of the pollen, or even of a fluid matter, may possibly be aided by the pressure or action of the angular solid bodies which surround this axis, and its dispersion would, no doubt, be assisted by the increased surface of its divided apex.
But whatever supposition may be formed respecting the economy of this part, it appears to me that as it is found in a second species of the genus, and of essentially the same 613] structure, though slightly modified, the angular bodies of the upper cell being only six in number, there can remain little doubt of its being really the male organ.
The genus Azolla was founded by Lamarck on specimens of the South American species entirely destitute of fructification, the remains of which only appear to have been seen more recently by Willdenow, who describes it as "a Capsula unilocularis polysperma."
REFERENCES TO TAB. 10.
Azolla pinnata.
1. Plant of the natural size.
2. — magnified.
