44 



PLANT STRUCTURES 



tinguish them from the ciliated sperms, or spermatozoids, 

 which have the power of locomotion, these motionless male 

 gametes of the Red Algae are usually called s;permatia 

 (singular, spermatium) (Fig. 28, A, s). 



The oogonium is very pe- 

 culiar, being differentiated 

 into two regions, a bulbous 

 base and a hair-like process 

 (trichoc/pie), the whole struc- 

 ture resembling a flask with a 

 long, narrow neck, excepting 

 that it is closed (Fig. 28, A, 

 0, t). Within the bulbous part 

 fertilization usually takes 

 place ; a spermatium attaches 

 itself to the trichogyne (Fig. 

 28, A, s); at the point of 

 contact the two walls become 

 perforated, and the contents 

 of the spermatium thus enter 

 the trichogyne, and so reach 

 the bulbous base of the oogo- 

 nium. The above account rep- 

 resents the very simplest con- 

 ditions of the process of fer- 

 tilization in this group, and 

 gives no idea of the great and 

 puzzling complexity exhibited 

 by the majority of forms. 



After fertilization the trich- 

 ogyne wilts, and the bulbous 

 base in one way or another 

 develops a conspicuous struc- 

 ture called the mjstocarp (Figs. 28, 29), which is a case con- 

 taining asexual spores ; in other words, a spore case, or kind 

 of sporangium. In the life history of a red alga, there- 



FiG. 29. A branch of Polysiphonia, 

 one of the red algae, showing the 

 rows of cells composing the body 

 (A), small branches or hairs (B), 

 and a cystocarp iC) with escaping 

 spores (Z>) which have no cilia (car- 

 pospores).— Caldwell. 



