74 



EVOLUTION OF PLANTS 



the procarp, or carpogonium is, in the lowest forms (Fig. 

 20, A), a single cell much like the oogonium of the 

 green algse, but there is no contraction of the egg-cell 



preliminary to fertil- 

 ization. There is a 

 more or less evident 

 prolongation, known 

 *- as the trichogyne (), 

 developed from the 

 carpogonium, and the 

 motionless sperma- 

 tium, on coming in 

 contact with this, 

 fuses with it and the 

 walls of both cells are 

 dissolved at the point 

 of contact, and the 

 contents of the male 

 cell pass into the 

 trichogyne and effect 

 fertilization. It is 

 probable that in most 

 cases there is a fusion 

 of the nuclei of the 

 spermatium and car- 

 pogonium, but it has 

 been claimed that 



FIG. 20. Fructification of the Red Algae ; 

 A, procarp, or female organ of one of 

 the simpler Rhodophycese, Batracho- 

 spermum ; t, the trichogyne ; c, the 

 carpogonial cell ; B, the same after 

 fertilization : an, the spermatium 

 united with the trichogyne ; sp, spores 

 budding out from the carpogonial cell ; 



C, the antheridium of Polysiphonia ; 



D, the multicellular procarp of Sper- 

 mothamnium; t, the trichogyne; E, 

 diagram of the procarp in the higher 

 Khodpphyceae ; t, the trichogyne ; x, the 

 auxiliary cell which is secondarily 

 fertilized and produces the spores. 

 (Figs. A, B after Davis; E, after 

 Phillips.) 



sometimes this does 

 >t occur, the fusion of the protoplasm being sufficient 

 u) insure fertilization. The result of fertilization is not 

 a resting-spore as in the green algae, but the carpogo- 

 nial cell sends out a large number of short branches 



