AMONGST 7 HE SEAWEEDS. 23 



portable book is the one by Shirley Hibberd, pub- 

 lished by Groombridge, which, for all ordinary 

 purposes, is more serviceable than many a far 

 costlier work. Landsborough's book is also cheap 

 and useful. For more advanced work it will be 

 necessary to procure some such treatise as Greville's 

 or Harvey's on British Algse. 



The classification of seaweeds is a much simpler 

 matter than is the case with more highly organized 

 plants. It is curious that there is a direct relation 

 between the colour and the mode of reproduction, 

 so that, roughly speaking, the arrangement of sea- 

 weeds according to colour will correspond to botani- 

 cal classification. The identification of genera 

 and species, however, will require the microscope. 

 There are three great primary divisions of marine 



(1) Olive-coloured (Melanospermete) ; 



(2) Red (Rkodospermece) ; 



(3) Green (Chlorospermece}. 



The olive-coloured kinds are mostly tough and 

 strong ; many are furnished with air-vessels, and, 

 in general, they grow near the shore. The 

 commonest of these are the well-known Fuci 

 (Greek phycos, a sea-weed), popularly called sea- 

 wrack. The commonest of all is the Bladder-wrack, 

 so called from the bladder-like air-vessels which 

 cover it and by which it is kept floating in the water. 

 Fucus nodosus (Fig. 4) is covered with large air- 

 cavities. F. serratus (Fig. 3) has saw-like edges to 

 the fronds, and is destitute of air-vessels. Another 



