RHODOPHYCEAE 219 



contact with the substrate swelUng up, branching and producing 

 suckers or haptera which are apparently capable of penetrating 

 dead wood or the tissue of brown fucoids. In the latter case there 

 is evidently a capacity for epiphytism once contact is secured, and 

 there is even some evidence of partial parasitism. In California, 

 P. naiadiim is an obligate epiphyte on Phyllospadix and Zostera, 

 two marine phanerogams. 



The gelatinous fronds of Porphyra, which are normally mono- 

 stromatic although they become distromatic during reproduction, 

 are composed of cells that possess stellate chromatophores with a 

 pyrenoid, the process of nuclear division being intermediate between 

 mitosis and amitosis. Reproduction is by means of monospores, 

 carpogonia, which have rudimentary trichogynes, and antheridia, 

 the carpogonial areas occupying a marginal position on the thallus. 

 All the frond, except the basal region, can produce antheridia, but 

 fertilization has never actually been observed although there is 

 strong evidence which suggests that it does take place. The male 

 thalli are paler in colour than the female, and each antheridial 

 mother cell gives rise to sixty-four or 128 antheridial cells, each of 

 which produces one spermatium. The fertilized carpogonium divides 

 into four or eight cells that represent primitive carpospores ; these 

 are typically diploid whereas here they are haploid because a form 

 of meiosis occurs when the fertilized carpogonium begins to divide. 

 The carpospores eventually germinate to form a creeping filament, 

 and it has recently been shown that spores from these threads 

 are liberated and when germination has commenced it represents 

 the commencement of a new Porphyra plant. It is suggested that 

 the protonemal stage is equivalent to an adelophycean or dwarf 

 generation in the life cycle, and further work on this part of the life 

 history might produce interesting results. 



The plant, which is called ''lava" in England, "sloke" in Ireland 

 and "slack" in Scotland, was formerly used as a food when it had 

 been boiled and seasoned with spices and butter. It is still used as 

 a food and medicine in Hawaii under the name of Lt?nu Luau. In 

 Japan, where there are over 2000 acres in cultivation, it is grown on 

 bamboo bushes planted out between the tide marks where there is 

 a depth of 10-15 ft. at high water. After collection, the plants are 

 stirred in fresh water in order to cleanse them, chopped up into 

 small bits, dried in the air and then pressed into sheets which, after 



