PLANTS AND ANIMALS DISTINGUISHED. 23 
all living beings, high or low, begins in a small round det 
of matter—in plants called an ovule, in animals, an ovum. 
This cell, or dot, contains a fluid, called protoplasm, iden- 
tical in composition and in function. In the very simplest 
forms the protoplasm is not inclosed by a membrane; but 
generally there is a cell-wall. In plants, with few excep- 
tions, this wall is of cellulose, or something akin to starch ; 
in animals, with few exceptions, the wall is a pellicle of 
firmer protoplasm, 2. é., albuminous. 
(2) Composition— Modern research has broken down the 
partition between plants and animals, so far as chemical 
nature is concerned. The vegetable fabric and secretions 
may be ternary or binary compounds; but the essential 
living parts of plants, like animals, are quaternary, con- 
sisting of four elements—carbon, hydrogen, oxygen, and 
nitrogen. Cellulose (woody fibre), starch, and chlorophyl 
green coloring matter) are eminently vegetable products, 
but not distinctive ; for cellulose is wanting in some plants, 
as Fungi, and present in some animals, as Tunicates ; 
starch, under the name of glycogen, is found in the liver 
and brains of Mammals, and chlorophyl gives color to the 
fresh-water Polyp. Still, it holds good, generally, that 
plants consist mainly of cellulose, dextrine, and starch ; 
while animals are mainly made up of albumen, fibrine, 
and gelatine; that nitrogen is more abundant in animal 
tissues, while in plants carbon is predominant. 
(3) Form.—No outline can be drawn which shall be 
common to all animals or all plants. The lowest members 
of both have no fixed shape. The seeds of Confervee can 
hardly be distinguished from animalcules ; the compound 
animals, Sea-mat and Sea-moss (Polyzoa), are often taken 
for sea-weeds; the trees mimic the branching Coral, and 
the Coral buds and blossoms like the Rose. The ideal 
form of a plant—-trunk, branches, twigs, special organs 
—is a form natural to all living matter enjoying rapid 
