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 



FIG. 20. Fructification of the Red Algae ; -1-1 _ , .-, 



A, procarp, or female organ of one of paSS 



the simpler Rhodophycese, Batracho- tlichoo'yne and effect 



spermum ; t, the trichogyne ; c, the 

 carpogonial cell ; B, the same after 

 fertilization ; an, the spermatium 



fertilization. It is 



budding out from the carpogonial cell ; 



C, the antheridium of Polysiphonia ; 



D, the multicellular procarp of Sper- 

 mothamnium; t, the trichogyne; E, 



united with the trichogyne ; sp, spores probable that ill most 



cases there is a fusion 

 of the nuclei of the 



diagram of the procarp in the higher cnprmatinm ami r>ar- 



Rhodophycese ; t, the trichogyne ; x, the 



auxiliary cell which is secondarily polonium, but it has 



fertilized and produces the spores. 



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



Phillips.) 



been claimed that 

 sometimes this does 

 not occur, the fusion of the protoplasm being sufficient 

 to insure fertilization. The result of fertilization is not 

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

 nial cell sends out a large number of short branches 



