PLANTS AND ANIMALS DISTINGUISHED. 
21 
CHAPTER II. 
PLANTS AND ANIMALS DISTINGUISHED. 
It may seem an easy matter to draw a line between 
plants and animals. Who cannot tell a Cow from a Cab¬ 
bage ? Who would confound a Coral with a Mushroom ? 
Yet it is impossible to assign any absolute, distinctive 
character which will divide the one mode of life from 
the other. The difficulty of defining an animal increases 
with our knowledge of its nature. Linnaeus defined it in 
three words; a century later, Owen declared that a defi¬ 
nition of plants which would exclude all animals, or of 
animals which would not let in a single plant, was impos¬ 
sible. Each different character used in drawing the boun¬ 
dary will bisect the debatable ground in a different lati¬ 
tude of the organic world. Between the higher animals 
and higher plants the difference is apparent; but when 
we reflect how many characters the two have in common, 
and especially when we descend to the lower and minuter 
forms, we discover that the two “kingdoms” touch, and 
even dissolve into, each other. This border-land has been 
as hotly contested among naturalists as many a disputed 
frontier between adjacent nations. Its inhabitants have 
been taken and retaken several times by botanists and 
zoologists; for they have characters that lead on the one 
side to plants, and on the other to animals. To solve the 
difficulty, some eminent naturalists, as Hackel and Owen, 
propose a fourth “ kingdom,” to receive those living be¬ 
ings which are organic, but not distinctly vegetable or 
animal. But a greater difficulty arises in attempting to 
fix its precise limits. 
