THE DEVELOPMENT OF* THE PLANT 55 



Here we have life in its simplest known expression. A 

 minute globule of plasm, often less than a thousandth of 

 an inch in diameter, lies like a mere speck of gum or 

 jelly on the field of the microscope. It has no organs, 

 in the ordinary sense of the word, no nucleus, and no 

 membrane. Its " life " consists entirely in absorbing 

 matter, by physical and chemical processes, from the 

 surrounding moisture, increasing in size, and then 

 breaking slowly into two daughter cells. 



Some such type may be taken as the early forerunner 

 of all the countless species of animals and plants that 

 now people the earth. At some date after the ocean had 

 sufficiently cooled to admit the presence of living things, 

 swarms of these " microbes " made their appearance in 

 it, as the outcome of that long evolution of protoplasm 

 which it is so difficult for us to trace. Whether these 

 early organisms were of an animal or a vegetal nature is 

 not so easily settled as is often supposed. The distinc- 

 tion between plant and animal is by no means easy when 

 we reach the simpler forms of life. In fact, not only is 

 the whole group of the Bacteria claimed by both the 

 zoologist and the botanist (though they are now generally 

 left to the latter), but fairly advanced creatures like the 

 Volvox are still much disputed. Movement is no test ; 

 the Diatom moves more freely and gracefully than the 

 Amoeba. Sensitiveness is not a rigid test, as many 

 plants are more sensitive than the lowest animals. The 

 usual test (though even this cannot be applied rigorously) 

 is whether the organism lives on organic or inorganic 

 food whether it takes its protoplasm ready-made from 

 other organisms, living or dead, or absorbs inorganic 

 matter and converts this into protoplasm. 



In this sense the first living things are generally 

 regarded as being of a vegetal nature, though there are 

 exceptions. Some writers, indeed, would put the whole 



