342 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



B. Regeneration. 



The union between stalk and calyx is extremely fragile, 

 and as a consequence the calyces are frequently lost. A 

 zone of regenerative cells occurs immediately below the 

 calyx, as in other Pedicellines, and from this it is renewed. 

 It is no uncommon thing to find a colony which has lost half 

 of its calyces, while at the same time many regenerating 

 ones occur. This species may be said to possess a second 

 regenerative zone — that from which the branches arise. 

 This region of branch formation is always in close relation 

 with the bulbous dilatations. It lies just beneath them, and 

 it is probable that it retains its power of external budding 

 for only a short time — only until the thick layer of the cuticle 

 becomes chitinized; but it seems to retain the power of 

 regeneration from the inner layer of cells for a much longer 

 time. An illustration of this is afforded by the condition 

 represented in fig. 14. Here an old stalk {o. sik.) had lost 

 calyx and upper phalanx, so that the distal end of the lower 

 portion was left entirely exposed at a point just below where 

 a muscular dilatation had occurred. At this part of the 

 stem no septum is found. Yet from the inner layer of cells 

 a young shoot has arisen with well differentiated calyx, 

 basal dilatation, and rigid portion. In the discussion pre- 

 viously mentioned, Dr. Davenport maintains the importance 

 of septa in enabling a regenerative zone to bud. On page 

 20, he says, " If we seek an explanation of the dissepiments, 

 I think it is to be found in the protection of the stock against 

 the influx of water and destroying organisms at the time of 

 the loss of calyx or lateral branches which would make 

 regeneration impossible." At the same time this writer 

 holds (p. 21) that "segmentation has succeeded, rather 

 than preceded, the condition of bud formation from the 

 stalk, it being desirable owing to the greater danger from 

 mutilation to which the stalk is exposed." From this point 

 of view, G. ramosa retains a primitive capacity in a high 

 degree in its ability to regenerate from a point where no 

 septum has developed. 



