100 



THE ALGAE 



* CODIACEAE : C odium (fleece). Fig. 56 



This is a widely distributed, non-calcareous genus with species 

 living in the warm and cold oceans. The spongy thallus, which is 

 anchored either by a basal disc or else by rhizoids, varies greatly 

 in form and appears as erect, branched, worm-like threads (C. 

 tomentosum group), flat cushions (C. adhaerens group), or as large 



56 Codium. A, plant of C tomentosum. B, C.fragile^ utricles. C, C. 

 tomentosum, single utricle with hairs. D, C. tomentosum, portion of 

 thaUus with medulla and cortical utricles. E-G, stages in formation 

 of constriction at base of utricle. H, propagule of C. isthmocladum. 

 I, C. tomentosum, female gametangium. J, C. tomentosum, male game- 

 tangium, K, C. tomentosum, juvenile thread. L, C. isthmocladum, 

 utricle with propagule. (A, after Taylor; B, C, E-G, J, after 

 Tilden; D, H, K, L, after Fritsch; I, after Oltmanns.) 



round balls (C. bursa group). In C. tomentosum there is a central 

 medulla of narrow forked threads and a peripheral cortex of club- 

 shaped vesicles which are the swollen apices of the forked threads. 

 Deciduous hairs may develop on the vesicles and scars are to be 

 seen marking their point of attachment, whilst annular thickenings 

 occur at the base of each vesicle and at the bases of the lateral 



