THE LIFE OF MAMMALS 
at all. Similarly the terms “beast” and “brute” are inaccu- 
rate or wrong; and so we are driven to borrow a term from the 
Latin to supply the need. This is the word ‘‘mammal” — 
a word easy to remember, definite in meaning, which 
ought to come as commonly and properly into use as 
“bird” or “fish,” since, like them, it stands for its whole class 
and for nothing else. This term expresses the one great dis- 
tinction which separates mammals from all other animals, 
namely, the feeding of their young upon milk, a nutritious 
liquid, rich in sugar and fats, secreted by the mother’s system 
in glands or milk bags from which the milk is sucked out by 
the little ones, whose stomachs, at first, can make use of no 
other kind of food. These milk glands are called in Latin 
mamma, whence the technical class name Mammalia, and also 
our English word ‘“mammal”’ — an animal that suckles its young. 
This fact alone, had we no other means of judging, would 
show us that the mammals stand highest in the scale of animal 
life. The simply organized animalcules, the lowly worms, 
shellfish, and insects, grow up without any parental attention — 
are simply tumed loose to shift for themselves. Very few 
fishes or reptiles take any special care of their little ones, and 
none feed them. In the case of many birds the young are able 
to run about and pick up their own living as soon as they emerge 
from the eggshell; and where they remain in the nest for a 
time and are cared for by the parents the food brought them is 
usually the same as that of the old ones. This state of things 
shows progress; and in a general way the rule holds that the 
higher the organization of the animal the more helpless are its 
young, and the more they need parental care, time to mature, 
protection, and special food. Hence the peculiar provision of 
the mother’s milk in this class is a sure indication of the high 
rank of mammals as a group; and the infants of the superior 
members of it depend upon their milk diet much longer than 
do the inferior members. 
Name. 
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