FERTILISATION OF RED SEA-WEEDS BY ANIMALCULE. 397 
It originates upon the female plant closely below the apex of 
the thallus-branches, and generally there are several of them 
forming successively at varying intervals from the branch-end 
downwards. 
Fig. 2 shows the carpogonium-bearing branch-end of a female 
specimen of Polysiphonia subulata ; cg’ is a very young carpo- 
gonium; ¢g, cg are two mature ones; ¢’ and ¢” two trichogynia; 
Vort. are two Vorticelle. The whole is magnified 800 times. 
In Fig. 3 a carpogonium (ca) is represented, magnified still 
more (480 times); Vort.is a Vorticella; ss the antherozoids. In 
the mature state the carpogonium consists of three essential 
parts, viz. :— 
1. The basal portion, f (Fig. 3). 
2. The fertile spore-forming part, ¢ 9. 
3. The hair apparatus, ¢ and gh. 
The basal portion (f) consists of five tubular cells running 
parallel to each other, of which in Fig. 3 only two are seen. Then 
follows the fertile part (cg), which is an oval cellular body, con- 
sisting of some 20 to 26 cells. A central cell, copiously filled with 
granular protoplasm, is surrounded by a number of irregular, peri- 
