290 ON THE IMPREGNATION OF VAUCHERIA SESSILIS. 
in Ferns, Mosses, Characeze, Lichens, and some other tribes. 
For the Characeze it may be sufficient to refer to the plates of 
Mr. Varley, in the ‘ Transactions of the Microscopical Society of 
London, vol. ii. ; and for the Lichens, to the valuable Memoir on 
Lichens by M. Tulasne, in ‘Annales des Sciences Naturelles,’ 
third series, vol. xvii., and the exquisite and inimitable plates il- 
lustrating the same. Nevertheless it has been reserved for the 
research of M. Pringsheim, of the Royal Academy of Berlin, to 
ascertain the true relation of these organs to each other, and to 
witness the singular and wonderful process of impregnation. His 
Memoir on the Impregnation and Germination of Algz is pub- 
lished in the Reports of the Berlin Academy, and an abridgment 
is included in No. 13 of Lankester and Busk’s ‘ Quarterly Jour- 
nal of Microscopical Science,’ illustrated by a beautifully engraved 
plate of coloured figures. 
The plant in which M. Prmgsheim witnessed this phenomenon 
was Vaucheria sessilis, DC.,a British plant, which has been found 
in autumn and early spring, forming broad green patches or float- 
ing masses on the surface of pools and ditches in Sussex, by Mr. 
Borrer. A representation of this plant, from specimens commu- 
nicated by Mr. Borrer, will be found in tab. 1765 of ‘ English Bo- 
tany.’? In the genus Vaucheria the female organs consist of ovate 
or rounded vesicles, sessile on the filamentary frond, either singly 
or in pairs, near to or between which arises a slender subulate pro- 
cess, curved at the summit like a horn or crook, which represents 
the male organ. These are well figured in the plate above referred 
to; and similar representations of the same organ in other spe- 
cies of the genus will be found in Greville’s ‘ Algz Britannicee,’ 
tab. 19, and Berkeley’s ‘ Algze,’ tab. 9, and ‘ English Botany,’ tab. 
1766, and in plates 2 and 3 of Vaucher’s ‘ Histoire des Conferves.’ 
In an early stage both the male and female organs were continu- 
ous with the parent filament; but at a certain period both be- 
came isolated by the development of a septum at the base of the 
female organ, or sporangium, and about midway up the hornlike 
process, or antheridium. Every part of the plant is similarly 
filled with elongated chlorophyll granules, imbedded in an albu- 
minous plasma and rounded oil-globules, which together consti- 
tuted a dense internal lining of the filament, between which how- 
ever and the true cellulose membrane is developed a thin, colour- 
less layer, designated ‘ cutaneous layer.” The sporangium now 
