1916 Hurd; on Codium 115 



length while some may be as much as 500 fx. The diameter is uniform ex- 

 cept where it tapers slightly at the base, and is about 30 [x in mature 

 hairs. The hairs are usually colorless, but often look granular (Figs. 

 26-32). 



Utricle hairs sometimes break off evenly just above the plug which 

 is usually present in the base, thus leaving smooth scars (Fig. 27), or 

 they may shrivel up without dropping off (Figs. 43, 44). KUster (11) 

 says that in C. tomcniosum the plug in the base is 1 -sided with an open 

 canal into the utricle, the canal remaining open until the hair breaks off. 

 In C. mucronatum this plug is not 1 -sided, nor does the canal always re- 

 main open in maturity. Kiister mentions the possibility of determining the 

 age of a utricle by the number of scars present, since new hairs grow in 

 a new spot when old ones break off. This is referred to by Oltmanns 

 (14) as the periodicity of the utricle hairs. The only evidence bearing 

 on this point obtained in the short time that the plants were under in- 

 vestigation by the writer was the fact mentioned above that the hairs 

 on any one utricle are usually of different sizes pointing to the possi- 

 bility that they do appear successively (Fig. 26). 



The function of the utricle hairs has not been definitely determined. 

 They were found on young and old plants, and on utricles bearing game- 

 tangia (Figs. 43, 44) ; but it may be significant that many plants on 

 which the hairs occurred very frequently, had no gametangia. One plant 

 was found with hairs longer than on the others, and in this plant they 

 were present on a larger number of utricles. Curiously, with few ex- 

 ceptions, there was only one hair on a utricle. Whether such variations 

 in size and occurrence are due to differences of environment was not de- 

 termined. Harvey (9) described the utricles of C. tomentosum as "clothed 

 with hyaline, soft, byssoid hairs which when expanded in water stand out 

 vertically and give to the branches the tomentose character." Their com- 

 parative rarity and colorless appearance in C. inucronatuvi suggest func- 

 tionless degenerate organs. 



Falkenberg (8) thought that the utricle hairs in C. tomentosum and 

 C. elongaium were degenerate gametangia, sometimes developing in place 

 of the latter. It is true that on some plants examined by the writer 

 gametangia were wanting and the hairs unusually common ; but the latter 

 originated nearer the tip of the utricle at a level above that at which 

 gametangia arise. This indicates a real difference in the two. Further, 

 it is not uncommon to find both gametangia and utricle hairs on the same 

 plant, and sometimes on the same utricle. 



Berthold (3) considered the utricle hairs of C. tomentosum a pro- 

 tection against intense light. He said that their development was di- 

 rectly related to the intensity of the light; that on shaded ])arts of the 



