108 POND LIFE, 



which we find in our fresh-water ponds. First, however, I wish 

 you to bear in mind that plants and animals are really parts of one 

 great whole, and that the inanimate world is to be put on one 

 side, and the living or animate world on the other. You are not 

 to go away with the old nursery division of the whole universe 

 into animal, vegetable, and mineral, because that is unscientific. 

 The division is not into three, it is only into two; the aimiiate and 

 the iiianimate. Plants and animals are very closely related, they 

 are distant cousins. So that if you had the first living thing, you 

 would find it had reproduced itself, and these reproductions 

 diverged into a family tree with two branches, the one of which 

 became plants and the other animals. The truth of this is very 

 easily seen when we come to study the lower forms of animal and 

 vegetable life. Of course, it is very easy to separate the higher 

 forms from each other, but when we come down to where the two 

 branches begin to diverge, we shall find that we cannot tell 

 whether a given form is a plant or an animal. In other words, 

 we get a group of forms that are equally related to animals and 

 plants, and it is very much more reasonable to regard them as all 

 belonging to one big family, rather than to separate them into two 

 families, and they thus form a group which has been called 

 Protista, from the Greek, meaning " the most primitive creatures." 

 One of these is a creature which is sometimes found in the 

 fresh-water pools ; it is known as Protamceba (Plate XII., 

 Figs. 25, 26). It consists simply of a lump of protoplasm (the 

 name given to living matter). If we examine this Protamceba 

 with the microscope, we shall find that it is a pulpy, almost 

 colourless, shapeless substance. 



Now, how do we know that this creature is alive ? We apply 

 our three tests to it. First of all, does it move ? You watch it 

 and it appears to be quite still, but if you make a drawing of it 

 and look at it again in a few minutes, and make another drawing, 

 you will find it is not the same shape as it was before. It shrinks 

 a little at one side and expands at the other, so that it is contin- 

 ually pushing itself out in certain directions, and so moves along. 

 Secondly, does it feed ? There are in the water in the ponds 

 numbers of very small plants (Diatoms), of which I shall have 

 more to say by-and-by. The Protamceba puts out these feelers 



