REJUVENESCENCE IN NATURE. 275 



D. 2 (Ascidium, Cladophora}. Free cell-formation in the 

 second sense, in which it was used for instance by 

 Nageli,* likewise comprehends two very different series 

 of cases, viz., either the origin is only so far free, that the 

 daughter-cells formed through the transformation of the 

 whole contents of the mother-cell (with or without division 

 of them), separate at the very moment of their consti- 

 tution, from the membrane of the mother-cell, by con- 

 traction of their mass, and separate from each other in 

 the same manner, as we have already examined under 

 A. 2 (formation of spores of (Edogonium}, D. 2 (Spharo- 

 pled) ; or the origin is free even in relation to the 

 definition of the boundaries of the original mass of con- 

 tents from which the new cell is formed, the daughter- 

 cells being formed, not out of the whole contents of the 

 mother-cell, but out of the separate, unconnected portions 

 of them. It is this last series of cases that especially 

 merits the name of free cell-formation, if this term is to 

 be retained; and then the circumstances whether the newly- 

 formed cells are applied upon the mother-cell (E. 1), or 

 not, and, in like manner, whether they subsequently 

 become connected together into a continuous tissue (as 

 we shall see in the endosperm-cells), or not, are to be 

 regarded as less essential. 



a. A free daughter-cell is formed around the primary 

 nucleus of the mother-cell. The case here mentioned 

 differs from those examined under A. 2, e.g. the formation 

 of the pollen-grain in its special mother-cell, in the cir- 

 cumstance that the daughter-cell does not take in the 

 whole of the contents of the mother-cell, but lies free in 

 the contents of the latter, so that other daughter-cells 

 may subsequently originate in the contents of the same 

 mother-cell. This strange and most rare case was 



* ' Zeitschrift,' 1846, p. 51, (Ray Translation, 1849, p. 123.) "In free 

 cell-formation a greater or smaller portion of the contents becomes isolated, or 

 even the whole contents of the cell. On the surface of this is formed a, complete 

 membrane, altogether free at its outer surface, (in contact neither with the 

 wall of the mother-cell nor those of its sister-cells.)" 



