1916 Hurd; on C odium dimorphum 215 



Although no specific reference to male gametes in C. dimorphum has 

 been found, Collins (4), Wille (15), Ernst (5), and Oltmanns (H) de- 

 scribe them for the genus Codium. They claim these gametes are formed 

 in gametangia with yellowish contents and are very much smaller than 

 the female gametes. Thuret (13) and Hauck (7) refer to zoospores in 

 this genus, and Went (14) found pathenogenesis. In case there are male 

 gametes in this species, those described in this paper are the female 

 gametes on account of their relatively large size. It is quite possible 

 that these are parthenogenetic. This would explain the rarity of male 

 gametes ; or it may be that the two kinds of gametes are produced at a 

 different season, in which case those found in late summer may be parthen- 

 ogenetic or asexual or functionless. 



A translation of Svedelius' (12) description of Codium dimorphum. 

 reads as follows: "The whole thallus divided into unequal lobes, ex- 

 panded above the substratum and adhering to it, about 5 mm. thick, 

 cushion-like, smooth, dark green, margins of the lobes pale, lobes either 

 just loosely held together or separated, hairs wanting; utricles of the ex- 

 terior stratum about 50|U, thick, of two kinds ; that is to say, on the margin 

 of the lobes they are cylindric-clavate to obovate-clavate, apex blunt and 

 either very much thickened or with a convex half-moon shaped callus, 

 chloroplasts and sporangia sometimes wanting, lower part more slender and 

 showing scarcely any difference in diameter from the threads of the in- 

 terior stratum; [the second kind with] apex slightly thickened so that 

 there is almost no protection through thickening of the membrane, chloro- 

 plasts numerous and sporangia present; sporangia about 40/x thick, 6 times 

 as long as wide." 



In order to make the description of the plant more complete, the fol- 

 lowing is suggested as embodying Svedelius' conception of it together with 

 certain other facts. It is specially desired to take the emphasis from the 

 dimorphism of the utricles in view of the fact that some plants have only 

 the thin-walled type while in others the thick-walled ones predominate, 

 not only "on the margin of the lobes" but all over the plant. Furthermore, 

 sporangia are frequently found on the thick-walled kind and on their 

 branches, in spite of the fact that Svedelius considers these branches the 

 homologues of the sporangia of the thin-walled type: 



Codium, dimorphum Svedelius, Svenska exped. t. Magellanslanderna 

 3: 300-304, 1900. Plant body dark green, irregularly lobed, cushion-like, 

 spongy in texture ; rarely more than 1 cm. thick, often deeply lobed ; pith- 

 filaments 12-30ja in diameter, with holdfast at base and utricle at upper end; 

 utricles 50-1 OOju, in diameter, cylindrical, truncate, often slightly constricted 

 just back from the tip, branching to form new filaments; end wall of 



