DRIFTING LIFE 113 



boxes covered with delicate, interlacing, hair-like pro- 

 jections. On Plate 88 are given drawings of some of the 

 commonest diatoms that would be found in any catch from 

 the northern and more temperate regions of the Atlantic 

 Ocean and the seas around its border. There are many 

 thousands of different species occurring in the world, and this 

 is no place to confuse the reader with a medley of Latin 

 names. For those who may take a deeper interest in making 

 the acquaintance of the different kinds of diatoms and who 

 find delight in observing the marvellously delicate and 

 beautifully designed structures of these minute plants 

 through the microscope, a list of literature will be found at 

 the end of this book. 



In addition to the diatoms there are other single-celled 

 organisms that help to swell the plant life of the drifting 

 community. They are especially remarkable because, be- 

 sides containing the colouring-matter of plants, they possess 

 two tiny structures like the lashes of a whip which by 

 vigorous waving motion serve as a means of propelling the 

 creature through the water. Now, a true plant derives 

 all its nourishment from gases and dissolved salts that 

 are absorbed through the cell walls ; it never takes in 

 solid particles of food as an animal does. Many of these little 

 creatures, which are called "peridinians," have no coloura- 

 tion and are able to swallow solid particles of food through 

 a small depression on their cell surface. There are, however, 

 a few which possess colouring matter and also swallow solid 

 particles ; because they are able to feed, like plants, and at 

 the same time utilize solid food like animals, they are 

 a continual source of bickering in scientific circles, the 

 botanists claiming them as plants and the zoologists 

 maintaining that they are animals ! 



Many of these peridinians consist only of a little naked 

 cell with its whip-like lashes, and are in consequence, 



