l86 CALIFORNIA ACADEMY OF SCIENCES. [Proc. .^d Ser. 



characteristics it is of great value, especially in indicating 

 the position of a sterile frond. 



As a rule, the thickness of the fertile part of the frond is 

 much greater than that of the sterile part. This seems to 

 be due to the swelling of the jelly surrounding the repro- 

 ductive bodies at the time of ripening. Also, wherever we 

 have a dioecious frond, or where the antheridia and sporo- 

 carps are born on separate portions of the plant, the thickness 

 of the antheridial portion is greater than that of the sporo- 

 carpic portion. This would bear out our hypothesis that 

 increased thickness is due to the swelling of the jelly, since 

 there exists a larger number of partitions consisting of jelly 

 between the antherozoids than between the carpospores. 



P. variegata exhibits a very marked thickness and strati- 

 fication of the jelly-walls surrounding the vegetative cell. 

 The walls of the vegetative cells of all fronds of this species 

 examined were of this nature; consequently the author feels 

 entitled to consider this a diagnostic character, the more so 

 as the only other Porfhyra which possesses much thickened 

 cell-walls differs widely from P. variegata in habit and 

 external characters. 



The plant here referred to is P. perforata f . segregata. 

 The walls not only of the vegetative cells but also of the 

 reproductive cells are much thickened, especially those 

 produced by the first reproductive division of the antheri- 

 dium. In fact, the upper and lower groups of antherozoids 

 are noticeably separated, which lends the cross-section of 

 the antheridial portion of the frond a most characteristic 

 appearance. 



The outer jelly-walls of nearly all the fronds examined 

 were infested with bacteria which formed narrow lines per- 

 pendicular to the surface of the frond, reminding one of the 

 canals formed by the "spermatium" at the time of the fer- 

 tilization of the "procarp", as described by Berthold (1882). 

 These "canals" were found in the jelly surrounding the 

 vegetative and antheridial cells, as well as in that surround- 

 ing the sporocarps. 



In regard to the shape of the vegetative cells, it may be 

 said that while in the monostromatic fronds the cells are 



