POND LIFE. 109 



until they quite enclose the unfortunate Diatom, and presently it 

 has in a very literal sense surrounded its dinner. Now as to the 

 third question, does this little creature produce beings similar to 

 itself? At times there forms a groove all round it, and by-and-by 

 it becomes completely split across, and we have two creatures 

 where there was only one before (Fig. 25). But that is not the 

 only way in which this takes place. Our Protamceha draws itself 

 up into a kind of globule, and then shrinks together, forming on 

 the outside a knob, the protoplasm inside of which divides into a 

 large number of portions, and each of these forms a fresh creature. 

 So that in these two ways creatures are formed like the original. 

 The Protamceha^ therefore, fulfils the three distinctions between 

 living and not-living substances. Now, is it an animal or a plant? 

 It is very difficult to say ; this species has always been placed in 

 text-books of Zoology rather than of Botany, but it seems, on the 

 whole, advisable to regard it as one of a group intermediate 

 between the animal and vegetable kingdoms. It is, in fact, a 

 representative of the very simplest form that a hving being can 

 exhibit. Much more common, however, is a creature which makes 

 a step in advance upon Protamceha, inasmuch as the central part of 

 its body seems to be drawn together into a more solid mass than 

 the rest, called a " nucleus." This is the Amceha^ and when it 

 is about to split into two, and thus reproduce itself, the nucleus 

 divides before the rest of the body. 



Now, there is a curious plant which is a step in advance of the 

 Amccha, sometimes found in the water and in damp places. It 

 forms a kind of jelly, and on examination with the microscope, 

 is seen to consist of a number of little cells, arranged in strings, 

 twisted and curled about in a serpentine manner (PI. XII., Fig. 24). 

 This is just one step in advance of the form we have been 

 considering, for that consisted of only one cell, but here a 

 number of cells are produced. Originally, however, it consisted of 

 one cell only, which split up and became two, and these in their 

 turn formed new ones, and so on. 



Another very curious plant is the Spirogyra (PI. XII., Figs. 

 19 — 23), which occurs very abundantly in the green scum on the 

 surface of ponds, and consists of a long string, divided into cells by 

 a number of partitions ; it is crossed by green colouring matter which 



