340 Mr. A. Henfrey on the Progress of Physiological Botany : 
recognized that the organ is a sac formed of a single layer of 
cells. This sac is filled with contents which appear granular and 
opake. It bursts at the apex and allows a quantity of minute, 
round cellules to escape. These cellules move about actively in 
water. Each contains a spiral fibre, which by tearing the mem- 
brane of the cellule becomes free, and then exhibits a motion 
similar to that of the spermatic filaments of the Mosses, Liver- 
worts and Charas. 
The course of development of these organs is detailed, and 1s 
to the following effect :—Certain cells of the pro-embryo grow 
out by their free surface ito processes which are gradually elon- 
gated and become divided by transverse septa, so as to resemble 
in some measure short and thick confervoid filaments ; the num- 
ber of superposed cells varies from two to five. Then these cells 
become multiplied by the formation of vertical septa, so that 
each is divided into five cells, four forming a peripheral layer in- 
closing one in the centre. The central cells of all the articula- 
tions become confluent into a canal running up the middle of 
the organ which thus becomes a sac, closed below by the cell of 
the pro-embryo and above by the four cells of the uppermost. 
articulation. This structure is usual, but slight modifications 
occur, not only in the number of articulations formed, determi- 
ning the length of the organ, but in the development of the par- 
ticular joints, the uppermost and the bottom one sometimes re- 
maining in the state of simple cells. 
The organs when fully formed have the central cavity so 
densely filled with the moving cellules, that they sometimes ap- 
pear like mere double or even simple sacs, the cells forming the 
walls being compressed by the internal expansion. 
The central canal at first presents an opake granular appear- 
ance ; subsequently the contents are converted into the above- 
mentioned cellules. The mode of development of these is dis- 
cussed by the author, and the analogous process in the anthe- 
ridia of other Cryptogamia referred to; he concludes that it is 
most probable that they are formed by a succession of develop- 
ments from parent-cells, the central cell of the five of each arti- 
culation being the primary parent-cells. 
The organs containing the spiral filaments discharge their 
contents when placed in water, even before they are fully deve- 
loped. In an undeveloped condition they appear as round vesi- 
cles ‘004: to ‘005 of a line in diameter, containmg homogeneous, 
or finely granular, colourless mucilage. Sometimes chlorophyll 
globules present themselves. Many possess a parietal nucleolus. 
The perfect cellules contain only a spiral filament. This usually 
has two turns ; sometimes only one and a half, sometimes two 
and a half or three. The filament has one broad and obtuse end, 
