ALG^E 75 



whose end-cells are the " carpospores " (Fig. 20 B, sp) ; 

 the whole mass of spores budded off from the fertilized 

 carpogonial cell forms the "sporocarp" or "spore-fruit." 



In the higher Rhodophycese, however, the cell which 

 hears the trichogyne does not itself produce the spores, 

 but there are certain accessory cells (Fig. 20 E, x) which 

 are impregnated, secondarily, by outgrowths from the 

 carpogonial cell, known as " ooblastema filaments." A 

 direct protoplasmic connection is thus established be- 

 tween the carpogonial cell and these auxiliary cells, 

 whereupon the latter begin to bud freely and produce the 

 spores much as these are formed from the carpogonial 

 cell in the lower forms. In certain types the auxiliary 

 cells are numerous and widely separated from the car- 

 pogonial cell. In such cases several very long ooblastema 

 filaments grow out from the latter after fertilization, and 

 these apply themselves to the auxiliary cell, which 

 thereupon produces a group of spores in the usual 

 way. In extreme cases a single ooblastema filament 

 may be sufficient for impregnating more than one aux- 

 iliary cell. 



From some recent investigations it appears that some- 

 times parthenogenesis may occur, i.e. the procarp may 

 give rise to spores without fertilization. How exten- 

 sive this phenomenon is, must be determined by future 

 investigations; but the rarity of antheridia in some 

 species, and the absence of spontaneous movement in 

 the spermatia make it not unlikely that parthenogene- 

 sis is not so rare a phenomenon as has usually been 

 supposed. Among the green algae parthenogenesis is 

 known to occur in Ohara crinita. 



