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 is 

 to the following efi^ect : — Certain cells of the pro-embryo grow 

 out by their free surface into 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 Une in diameter, containing 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. 



