225 



KNOWLEDGE c^ SCIEXTIEIC NEWS. 



[Sept., 1905. 



Fig. 5 — b is a view of the very tip of a Ceramium frond, 

 showinir the regular method of cell division. 



Other red seaweed.s show their beauty without the 

 aid of the microscope, .\mong them are the Pttlota. 

 a splendid feathery plant, growing on stalks of the big 

 Tangles, and the Mermaid'.s Comb (Plccamiiim), 

 happiest below low-water mark, and easily recognised, 

 because the frond bears branches on one side only, 

 like the teeth of a comb, and these repeat the process. 

 Fig. I ! shows a .snipping of the frond enlarged. Others 

 are Chilocladia, with sprays like branching rows of 

 eggs, or beads, CoraJlines, with a white skeleton of 

 carbonate of lime— formerly believed to be an animal 

 allied to the corals— and the broad, leafy forms in great 

 variety, from I'orphyra, a flat sheet of cells, several 

 inches across, lying flat and black on the rocks when 

 the tide is out'; Irish Moss (Chondrus), with a flat 

 dichotomous frond, often rather curly ; and a host of 



others, till we reach the Rhodymenias, with frond of 

 various patterns, and the Delesserias, with leaves ex- 

 actly like those of land plants— midrib, veins, and all 

 complete. Fig. 6 is part of a frond of R. laciniata, 

 natural size ; Fig. 7 is R. palmate, half size, and Fig. 8 

 is D. sanguinea, natural size. 



The Irish Moss is one of the few seaweeds that are 

 put to any use. It is still gathered, wa.shed in Iresh 

 water, and dried, and in this state .sold by the chemist 

 for making jelly. The reader with a turn for experi- 

 ment will be able to test its "virtues" for himself. 

 We must not omit to mention, however, that the 

 WTacks are also useful to man. They are still largely 



used for making washing soda. The dried wrack is 

 burnt, and the a.sh (known as " kelp'") is thrown into 

 water, when the s<Kla dissolves, and can be easily 

 crystallised out. (.Another ea.sy experiment for the 

 enthusiast, best not performed in your seaside lodgings, 

 as the special perfume produced in the burning d<x:s 

 not commend itself to many.) 



Burning reminds us of drying, and drying reminds 

 us that the visitor to the seaside may wish to take dried 

 specimens home. There arc two difficulties to sur- 

 mount in drying seaweed. The first is the salt in them, 

 which is got rid of by a good soaking in fres/i water. 

 'I"he second is the gelatinous nature of the frond of 



many of them, which causes them to stick to the drying 

 paper. To prevent this, put between the seaweed and 

 the paper a clean linen rag — old handkerchiefs are as 

 good as anything else for the purpose. The stickiness 

 of so many seaweeds can. however, be made use of, for 

 if vou take the paper on which j'ou intend to finally 

 mount the plajit, and slip it into the lx)wl of water 

 under the seaweed, }ou can then gently raise the paper 

 with one hand, and with the other spread out the whole 

 plant as it floats upon the paper. The most delicate 

 plants can be easily mounted in this way. ' Now cover 

 with rag and dry Ix-twcen drying papers. 'Ilie plant 

 will adhere firmly to its mount, while the linen prevents 

 it adhering to the drying paper. 



In searching for red seaweeds, it is well to look out 

 for fruiting specimens. The process by which the egg 

 cells are fertilised in the red seaweeds is very much 

 more difficult to follow than in the brown seaweeds, 

 but the result — the fruit — can, in many cases, be seen 

 with the naked eye. It is sure to be found in summer 

 on some of the Ceramiums (I'ig. 5 — c) and Poly- 

 siphonias, and when it is found on that fine plant Ptilota 

 (a plant growing on the stalks of Tangles), it forms a 

 very fine microscopic object. Fig. 2 — c is a snipping 

 of Polysiphonia with the male organs (antheridia). 



The red seaweeds, however, have two strings to 

 their bow. Tliey produce not only fruit, by the union 

 of male and female elements, but spores, without the 

 need of such union. These ahvay.s come in groups of 

 four, and are hence called tdrasporcs. When these 

 tiny spores are set free, they develop into new plants. 

 .Some plants have them outside, either sessile or grow- 

 ing on short stalks, while others have them inside, 

 buried in the frond. They are easily seen with a Ions, 

 and better with the micro.scope. Callithamnion (the 

 ' bonny bush " mentioned above) is a beautiful object 

 when it bears si)ores (Fig. 1 — /;, i). .So is Nitophylhini, 

 a pretty common plant with a broad flat frond. It 

 shows on its surface distinct spots where the buried 

 tetraspores occur. . . . (Fig. 9). A spore-bcaiing 

 tuft of Rhodomela, about ,i, inch long, is shown en- 

 larged in I'ig. 3 — b ; and a small portion of it is again 

 magnified in Fig. 10 — h, where the dark spots are seen 

 to be groups of spores, four in a group, but only three 

 visible. These figures may be compared will) those of 

 Polysiplionta (Figs. 2 — b and 10 — a), in the last ol 

 which one of the barrel-shaped segments has burst and 

 discharged the spores. I""ig. 5 — d is a bit of a 

 Ceramium frond with tetraspores. 



The red seaweeds appeal to the most cursory wan- 

 derer on the rocks, f)n account of their numerous and 

 varied forms, and their obvious beauty. But the 

 fortunate possessor of a microscope will soon find a 

 wealth of liidden l>cauty in them which will much more 

 than fulfil any expectations which this short article may 

 have aroused. 



It remains to say a few words about the Green .Sea- 

 weeds, which have charms all their own. and these will 

 form the subject r>f the third ;incl last article. 



The Word "Patent" 



With reference to a letter appearing in our July luimlier, 

 " W." writes to ask if the word " I'atcnt " is not merely a conden- 

 sation of " Pattern entered." It is uat, IxiiiK derived from the 

 Latin pateo, "to open," Letters patent being " opon to the 

 perusal of all." I'attern is derived from tin; I'rcncli /■a/co;/, 

 an original model to be copied. 



