THE OCEAN FEEDING-GEOUNDS 87 



forms are widely varied : some are spherical, some 

 cylindrical, some spindle-shaped, &c. Sometimes they 

 are united in circular or rectilinear colonies. The 

 Peridinaceae may be recognised by their long mobile 

 cilia, which are known as flagellae. They are clad in 

 a thick cuirass, which is ornamented with three or four 

 very fine spiny projections. The Cyanophyceae are 

 filamentous algae. Besides these three groups there are 

 the green algae, which are associated in colonies, and are 

 bathed in a gelatinous magma. It goes without saying 

 that the eggs and spores of these tiny organisms also 

 form part of the vegetable plankton. 



Animal plankton is composed of tiny microscopic 

 creatures belonging to the Protozoa, and ciliated or 

 flagellated ; Radiolaria, with finely worked flinty shells, 

 and Globeriginae, with smooth calcareous shells. It 

 also contains immense quantities of tiny crustaceans, 

 invisible to the naked eye, and of Copepoda in particular. 

 The Copepoda have elongated segmented bodies, but no 

 carapace, and carry two pairs of swimming antennae. 

 As in the vegetable plankton, the eggs and larvae of all 

 these little organisms go to make up the mass of 

 plankton together with the adult organisms. Plankton 

 also contains the eggs and spores of almost all the 

 marine algae of the continental plateau, the eggs and 

 larvae of nearly all the marine invertebrates, even of 

 those which when adult are the most securely attached to 

 the rocks or hidden in the sand ; and the eggs, the larvae, 

 and the fry of many fish, even of those which, like the 

 sole, spend their adult life upon the bottom. If I may be 

 allowed the comparison, plankton is like a vast city full 

 of inhabitants who are born, live, multiply, and die, and 

 also of passing visitors, who come from all parts of the 

 world in their infancy and return thither as they grow up. 



