March, 1907.] Cymathere, a Kelp from the Western Coast. 91 



a coast where it is well developed its young plants may be seen 

 everywhere between the tide marks even up as high as any of 

 the "kelps grow, w^here they must soon perish because of the 

 unsuitalDle conditions. They are much the most abundant of 

 all the young kelps to be found even in high levels. The young 

 of Cymathere though it grows much closer to the tideline than 

 Nereocystis, are not often found growing uncoA^ered at low water 

 and are verv much less abundant though the adults are by no 

 means scarce at Port Renfrew. 



In its histology Cymathere offers some points of interest. As 

 to the presence or absence of mucilage ducts there seems to be 

 some question since De Toni "95 contradicts Kjellman '93 by 

 asserting that they are present. In the specimens which I have 

 examined the stipe is wholly without ducts of any kind, while 

 in the lamina there occurs an irregular circle of openings which 

 mav be considered mucilage ducts. But they are not definitely 

 developed tubules with a lining wall of special secreting cells as 

 MacMillan '99 reports in Nereocystis; nor are they in a closely 

 crowded circle of definite position as in Laminaria bongardiana 

 or in L. btiUata as figured by Miss Mueller '04, fig. 8. They 

 appear rather as a local gelatinization and breaking down of 

 certain cells, perhaps the beginning of degeneration. To the 

 writer it seems most likely that their presence or absence is a 

 verv variable character which might not appear in younger, more 

 vigorous material. This if true would explain the disagreement 

 of the authorities cited. A similar breaking down of certain 

 cells mav sometimes occur in Renjrewia parvula but very much 

 less abundantly. In this case I did not consider the cavities 

 thus formed mucilage ducts because they seemed simply path- 

 ological alterations of the tissues and not normal occurrences. 



In places the inner cortex is developed into thick walled 

 strengthening tissue as is usual in the family. It is of such 

 sclerenchyma that the ribs on the folds are formed and to it they 

 owe their strength. The greater thickness of the ribs beyond 

 that of the rest of the lamina is entirely due to the extra develop- 

 ment of this tissue. 



The development of the sporangia follows closely that of 

 other kelps. MacMillan's '99 figures of the early stages of their 

 development in Nereocystis might almost bave been drawn from 

 my own preparations of Cymathere. The separation of the 

 pellicle from the sorus takes place after the following fashion: 

 The outer cell walls of the epidermis of the txnaltered lamina 

 form a rather thick cuticle over the surface. When the epider- 

 mis divides into the two layers which go to form the paraphyses 

 and the sporangia, the daughter cells secrete for themselves new 

 cell walls, at least on the external and lateral faces, leaving the 

 old cuticle with the partitions between the cells, free and hang- 

 ing to the lamina only by the bases of the latter. On the elon- 

 gation of the paraphyses these connections are broken and the 



