692 
PROCEEDINGS OF THE SOCIETY. 
which had been read appeared to throw new light on these various modes 
of reproduction, and seemed to point to the removal of the diatoms from 
the Protophyta, where they are placed in the Journal of the Society, 
to a position among the Conjugate, near to the desmids. 
Before the reading of Mr. Newton Coombe’s paper, the lantern-slides 
described below were exhibited, illustrating the formation of megafrus- 
tules of freshwater diatoms, and of the cysts referred to in Wm. Smith’s 
‘ Synopsis,’ and erroneously supposed to contain “ broods of young 
diatoms,” and to be a stage in the reproductive process. 
Nos. 1, 2, 3, and 4 (taken at a magnification of 312 diameters) were 
photos of cysts containing various species of diatom, Synedra radians 
(1), Gomphonema acuminatum (2), Eunotia pectinalis (3), Meridian circu- 
lar e (4). 
No. 5, of the same magnification as the cysts, was that of a Bhizopod, 
similar to those which formed the cysts, but with its tentacles contracted 
after death. The creature spreads its amoeba-like body over the diatoms, 
and after digesting their contents, makes its exit from the cyst by means 
of a small opening which can generally be detected by careful focussing. 
Mr. Coombe was led to the conclusion that the cysts did not contain 
“ broods of young diatoms,” as supposed by Wm. Smith and others, by 
discovering several containing two quite distinct species of diatoms mixed 
together. 
No. 6 was that of two frustules of Gymbella lanceolata lying side by 
side in a cyst (secreted by the diatoms) prior to conjugation (x 312). 
No. 7 showed the same species of diatom, with two megafrustules 
fully formed, as the result of conjugation of the parent frustules 
(X 312). 
No. 8 was that of two frustules of Gymbella parva, showing the actual 
intermingling of their contents prior to the formation of two megafrus- 
tules ( x 325). 
No. 9 showed the formation of two megafrustules of Gymbella cistula 
after conjugation ( X 325). 
No. 10 showed Gymbella lanceolata in cyst after conjugation, and the 
formation of two megafrustules, one of which had only just emerged 
from the parent frustule, and had not yet begun to silicify. The entire 
outline of this undeveloped frustule can be traced in the photomicro- 
graph (x 200). 
Ncs. 11, 12, 13, and 14 were further illustrations of the formation of 
megafrustules of Gymbella after conjugation ( X 300 about). 
No. 15 was that of a single frustule of Gymbella lanceolata , forming a 
megafrustule without conjugation. 
Nos. 16, 17, 18, and 19 illustrated a mode of conjugation differing from 
the preceding, in that the contents of the conjugating frustules, instead of 
growing, after emergence and union, in a direction parallel to the longer 
axis of the diatom, grow at right angles to the longer axis, with the 
result that the two megafrustules lie across the two microfrustules. It 
is difficult to take anything like a satisfactory photomicrograph of the 
two pairs of frustules which, from their position, as indicated, are neces- 
sarily in different planes from each other. The only genera in which 
Mr. Coombe had met with this particular mode of formation of the mega- 
frustules were Epithemia and Amphora. No. 19 showed the newly emerged 
