422 Prof. Henfrey on the Cell-contents of Closterium. 



over, that there are two currents, going and coming j side hy side, 

 on each side, I have found a current towards the end of the cell 

 running along the inner surface of the cell-wall on both sides, 

 and a counter-current running down in contact with the surface 

 of the green jelly-like endochrome. This gives rise to a double 

 eddy at the ends of the cell, which keeps the vacuoles in motion. 

 The two currents running together at the ends, both turn round 

 and return down the sides of the vacuoles to run towards the 

 centre of the cell in contact with the green endochrome. This 

 double current on each side accounts for the irregular move- 

 ments of the larger granules which are seen moving about, 

 and, as above mentioned, are often finally deposited in the va- 

 cuoles. When in the submarginal space, they naturally fall into 

 the intermediate central tract between the two currents, and are 

 thus urged this way or that way, according as they come more 

 extensively in contact with one or other. 



It is curious to contrast the conditions here with those in 

 Chara. There, the chlorophyll-layer is outside, next the cell- 

 wall, and the circulating protoplasm within ; here, the circulating 

 protoplasm is next the cell -wall, and the motionless chlorophyll- 

 mass occupies the centre. I am not positive whether the green 

 endochrome is solid or hollow ; I think solid, but densest at the 

 outer part. 



When the cell is ruptured by pressure, the colourless circu- 

 lating protoplasm absorbs water very rapidly, and, expanding, 

 drives out the green matter with force ; if the orifice is small, the 

 chlorophyll-corpuscles and other more solid parts of the green 

 jelly, being resisted to some extent by the borders of the orifice, 

 are jerked out with considerable force. I think this affords an 

 explanation of the mode of escape of zoospores from the cells of 

 Confervse in general. The appearances are just the same, and 

 a quantity of colourless, finely-granular protoplasm is always 

 found around and among the zoospores in the cell, and is left 

 behind when they escape. When the cell-wall is ruptured, this 

 matter absorbs water greedily, and ejects the semi-solid zoospores, 

 which often do not acquire their cilia and independent power of 

 motion until free. 



When the green matter of Closterium escapes into the water, 

 it quickly becomes vacuolated and blown out into a froth-like 

 mass, which soon coagulates. The conditions of the contents 

 after their escape into the water afford full proof of the charac- 

 ters of the cell-contents as above described. They consist of 

 fiuid and solid substances, of different degrees of density, 

 and presenting striking distinctive characters ; the outer circu- 

 lating fluid being thin and finely granular, and the green endo- 

 chrome semi-gelatinous, and even still denser in the longitudinal 



