326 Dr. 1\ Cohn on a new genus of ike family 0/ Volvocinese. 



they diverge widely at the other, and thus they look like a kind of 

 basket composed of eight pieces, like the gaping dental apparatus 

 of a Chilodon. 



Besides the two cilia which pass out from each primordial-cell, 

 through the orifices of the envelope-cell into the water, the 

 former very frequently send out other prolongations, which how- 

 ever do not perforate the envelope-cell. These are colourless 

 mucilaginous filaments, going out from each primordial- cell, espe- 

 cially from the ends of their longer axes, and which hence present 

 themselves especially clearly in the equatorial view. The ends 

 of the primordial-cells are mostly not green but colourless, and 

 elongated into numerous, likewise colourless, broader or thinner 

 bristle-like processes, which run out like rays in all directions, 

 are often ramified, and are attached to the inside of the envelope- 

 cell, without however perforating it (figs. 2, 4, 5). If these fila- 

 ments are much developed, they form a proper network, which 

 maintains each primordial-cell floating in the common envelope. 

 The extremities of the primordial-cells ai-e also frequently divided 

 dichotomously into colourless mucilaginous bands, which again 

 branch into radiating filaments and thus produce the most won- 

 derful forms. These colourless, filiform prolongations of the 

 primordial-cells may also be seen in the polar view, stretching 

 in all directions, and giving the total structure a most strange 

 aspect, almost similar to that of a Xanthidium (PI. VI. figs. 6, 7). 



In the internal organization of the primordial-cells, all that 

 can be made out is a green-coloured, softish substance of which 

 they are composed, and in which numerous delicate granules or 

 points are imbedded. When the primordial-cells are actively 

 vegetating, they are of a transparent vivid green ; but the colour 

 exhibits various tints ; in the youngest conditions it is purer, 

 more yellowish green, less obscured by dark points ; in the largest 

 forms, on the contrary, the contents appear bi'ownish gi-een and 

 opake, with the dark granules multiplied to such an extent, that 

 the whole almost loses its transparency. In the middle of the 

 primordial-cells are found two larger, nucleus-like vesicles, mostly 

 symmetrically placed, and these examined separately appear 

 annular, so that they possess an internal cavity ; iodine colours 

 them remarkably dark, with a violet tinge (figs. 2, 3, 4, 5). The 

 centre of each primordial-cell is frequently occupied by a lighter 

 circular space, which however does not vanish periodically, and 

 therefore cannot be regarded as a contractile vesicle. 



The primordial-cells are not surrounded by any special rigid 

 membrane-, and this is not only made evident by the multifold 

 changes of form which they undergo in the course of vegetation, 

 and by the filiform prolongations and ramifications which are 

 produced -directly from their substance, but is clearly shown by 



