CHAPTER I 



some rays and giving out others. In this case it changes blue rays to 

 some extent to red, yellow and orange ones, and so enables the 

 chloroplasts to perform their mission. 



Red Algae that grow near the shores are not usually brightly colored, 

 in fact they are almost sure to be mistaken for green Algae by the 

 novice. The genus Gigartina illustrates this fact well. Gigartinas 

 are very common on our coast. They are characterized by little ele- 

 vations, some of which bear globular spore fruits. One species, 

 Gigartina horrida, has very narrow divisions so that the plant resem- 

 bles bunches of coarse, dark green chenille. Another species has 

 fronds so wide that the children call it apron kelp. This grows in 

 deeper water and is a deep purplish crimson. There are interme- 

 diate species that show all possible graduations of color, according to 

 the depth of water. As these Gigartinas bleach on the beach they 

 present a great variety of color, the red or purple color fading to pink, 

 and finally vanishing and exposing the chlorophyll, which in turn 

 fades out. This fact has given rise to the term " calico " kelps that 

 children often apply to them. Our most common red, feather moss, 

 Plocamium, and many other delicate and brilliantly colored species 

 grow in deeper water. Another common genus among red Algae is 

 Corallina, named from the resemblance to coral. And here again the 

 idea of the similarity in form of lower plants and animals can be im- 

 pressed, for coral is animal, but Corallina is plant, while a very pretty, 

 graceful thing that they will call brown feather moss, seems much 

 more like a plant than does Corallina, but it is really animal, a hydroid. 

 The Corallinas are small jointed plants and are very brittle when 

 dried, because of the amount of lime they contain. Like the Gigar- 

 tinas, these plants show the presence of chlorophyll- as the red pig- 

 ment fades. The use of the joints to the Corallina and the fine dissec- 

 tions to the Plocamium and other red sea moss can be thought out. 



With the microscope many interesting facts of cellular structure 

 can be shown. The filamentous Algae consists of rows of cells ; the 

 very thin fronds have their cells arranged in but one or two layers. 

 A section through some of the thicker fronds, like the rock weed, 

 shows cells irregularly netted or interwoven, compactly at the outside 

 but very loosely within, a structure which is obviously adapted to the 

 environment of the plants. If it seems best to the teacher, some facts 

 of reproduction may be taught, but they must, in elementary work, 

 be taken mainly on authority. The marine green Algae reproduce by 

 zoospores. Many brown Algae, and all red Algae also reproduce 

 assexually, i. e., by simple cell division into spores, either zoospores or 

 non-motile spores. But some brown Algae, rock weed and sea oak for 



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