1916 Hurdj on Codium 121 



Saunders (16); San Juan Harbor, Strait of Juan de Fuca, Vancouver 

 Island, B. C, Tilden (17); San Juan Island, Muenscher (13); "under C. 

 tomentosum," Whidby Island, Port Townsend, Ludlow Bay, Wash., 

 Gardner (17); Sitka to the California Coast, Saunders (15). 



SUMMARY 



1. The plant adheres to the substratum by means of a large number 

 of holdfasts which are the expanded bases of pith-filaments. These, to- 

 gether with horizontal branches of the filaments and their utricles, con- 

 stitute the holdfast-cushion. 



2. Utricles of the holdfast-cushion vary in size and shape more 

 than do those of the frond, and do not bear gametangia. 



3. Normally the utricles of this species do not branch. 



4. The mucron is originally the thin-walled pointed tip of the 

 utricle, which is gradually filled solid by the deposition of successive 

 layers of material on the inside. 



5. The layers composing the mucron are often not tightly appressed 

 to the preceding layers so that there is a row of compartments extending 

 to the tip in an otherwise solid mucron. In shorter mucrons, the forma- 

 tion by layers is often indicated only by faint striations. 



6. Plugs, like mucrons, are formed by the decomposition of suc- 

 cessive layers of material on the inside of the filament. They completely 

 close the tube and so serve to keep the easily flowing contents of the plant 

 more evenly distributed. 



7. There is only one plug near the base of each utricle in the pith- 

 filaments, and that on the upper side of the utricle ; instead of two, one on 

 either side of the origin of the utricle, as commonly described for C. 

 tomentosum. 



8. Utricle hairs are found only occasionally, usually 1-4 on a 

 utricle. 



9. Utricle hairs may appear on the same utricle with a gametangium 

 although some mature plants were found on which utricle hairs were un- 

 usually common and gametangia were wanting. 



10. The failure of all efforts to find male gametes suggests partheno- 

 genesis. 



11. Gametangia are most abundant within two inches of the tips 

 of the fronds, and are not found at the base. 



