260 



PLANT STUDIES 



tinguish them from the ciliated sperms, or spermatozoids, 

 which have the power of locomotion, these motionless male 

 gametes of the Bed Algae are usually called spermatid 

 (singular, spermatium) (Fig. 228, .4, s). 



The oogonium is very pe- 

 culiar, being differentiated 

 into two regions, a bulbous 

 base and a hair-like process 

 {tricliogyne)^ the whole struc- 

 ture resembling a flask with a 

 long, narrow neck, excepting 

 that it is closed (Fig. 228, 

 J, 0, t). Within the bulbous 

 part fertilization usually takes 

 place ; a spermatium attaches 

 itself to the trichogyne (Fig. 

 228, 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 

 represents the very simplest 

 conditions of the process of 

 fertilization 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 de- 

 velops a conspicuous structure 

 called the cystocarp (Figs. 228, 229), 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- 



PiG. 229. A branch of Polysiphonia, 

 one of the red algae, showing the 

 lows of cells composing the body 

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

 and a cystocarp (C) with escaping 

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

 pospores). — Caldw^ell. 



