PROCEEDINGS OF -SOCIETIES. 79 
from the osculum when partially expanded was extremely 
languid. The author concluded by observing, that the 
structure and habits of the fresh-water sponges were in 
perfect accordance with those of the marie species. 
On Flustrella hispida. By Dr. Reprern. 
Tue author pomted out numerous inaccuracies in the 
existing descriptions of Flustrella hispida, under the names 
of Flustra hispida and Flustra carnosa—veferring especially 
to the facts that no spimes are ever to be found on that side 
of the ‘aperture of the cell next its base; and that whilst in 
specimens gathered in Kincardineshire the spines are placed 
on the septa all round the cells, in those gathered in Dublin 
Bay the spines for the most part form a semicircle over the 
aperture, two or three only being found on the sides of the 
cell in rare instances. The Doctor then described the struc- 
ture of the polypide after its removal from the cell, and its 
development by germination, describing its various stages 
from day to day, as it grew from a mere projection on the 
wall of the original cell, up to a complete cell with its spines 
and fully protruded polypide. The various characters of the 
perfectly formed zoophyte, with its cells set with spines; the 
most prominent features of its anatomical structure, and the 
growth of the new being from day to day by germination, 
were illustrated by a series of coloured drawings made by 
the author with the camera lucida; and microscopical 
preparations exhibited to the Section showed the characters 
of the cell, and of the polypide after its removal. 
Monday, August 31st, 1857. 
PHYSIOLOGICAL Svun-section. 
On the Alternation of Generations and Parthenogenesis in 
Plants and Animals. By Dr. LanKestER. 
Arter alluding to the phenomena of “ Alternation,” as 
described by Steenstrup in the Entozoa, Meduse, and Sertu- 
larian polyps, and to the phenomena of Parthenogenesis, 
described by Owen and Von Siebold, the author concluded 
his paper as follows: “ If we turn now to the vegetable king- 
dom, we find perfectly analogous phenomena presenting 
themselves. In fact, the modifications of the reproductive 
function, which have recently excited so much surprise, in 
the animal kingdom, are the normal forms of the function 
among plants. In the roots and branches of a tree we have 
a gigantic ‘ nurse,’ and the buds are its progeny. Just as we 
find the same secondary products called ‘gemmez,’ in animals 
