REJUVENESCENCE IN NATURE. 307 



where belonging to the development of the combined 

 organism, appearing as a mode of reproduction, so also 

 in the higher groups of the Vegetable Kingdom, we see 

 Sprout-formation extricated in most varied ways from the 

 subordinate relation to the " whole" of the vegetable 

 stock, and serving for the formation of independent indi- 

 viduals.* 



The interweaving of the reproduction and the indi- 

 vidual development is exhibited in a very strange manner 

 in that division of the Vegetable Kingdom in which a 

 decided contrast of sexes first appears,! namely, plants of 

 the Moss and Fern kind, in which the fertilization, — 

 which we have been used, from its mode of occurrence in 

 the whole realm of the Phanerogamia, as well as in the 

 Animal Kingdom, to imagine connected with the origin of 

 new individuals, — does not coincide with the commence- 

 ment of the individual cycle of development, but on the 

 contrary falls in the middle of this, becoming the means 

 of transition from a lower to a higher stage of the meta- 

 morphosis. In both cases it is a single celiin which the 

 subsequent development is called forth through the influ- 

 ence of the male sex, but in one case it is the primary 

 cell of the entire generative cycle, i. e. of all the cells 

 which, by their connected succession, represent the indi- 

 vidual ; in the other case it is a cell occurring within the 

 cycle itself, and merely forming the beginning of a new 

 segment of it. In the Phanerogamia it is the germ-cell, | 

 formed, after the entire accomplishment of the meta- 

 morphosis, in the uppermost central cell of the seed- 

 sprout, (the enibryo-sao of the ovule,) which receives the 

 impregnation by means of the advance of the pollen- 

 tube up to the embryo-sac ; with it the entire individual 



* Reproduction by propagula, (in the Mosses and Liverworts,) by 

 bulbels, runners, tubers, &o., see p. iO. 



f (This expression, as well as various other references of the same nature, 

 must be checked by comparison with subsequent researches. Thuret, 

 Nageli, Itzigsohn, Tulasne, Berkeley, and Broome, have pointed out con- 

 ditions indicating that sexuality is universal. — A. H.) 



t See p. 276. 



