120 HOW HE IS MADE 
off, as sharply as if cut with scissors. They leave 
the edges of the feathers notched in queer ways, 
but as they lay over each other that does not 
show. 
Birds in this way can change color without 
changing their feathers. While moulting but 
once a year, they can show two suits, and by 
partially moulting twice, can show three suits. 
Another thing about the color of feathers is 
interesting. Some colors, such as black, and red, 
and brown, are caused by coloring matter in the 
feather. But other colors are only an effect of 
the way the feather is made, whether it has 
ridges on it, or certain minute specks under the 
surface, which seem to act as prisms (says Dr. 
Newton), and reflect the light in different colors. 
For instance, green is always due to some 
shade of yellow coloring matter under a surface 
full of lengthwise ridges, and other colors are 
made in similar ways. 
These curious facts have been found out by 
that tell-tale little instrument the microscope, and 
no doubt it will reveal many more secrets in time. 
Color is useful to birds, as well as beautiful. 
Its great use is to conceal them from their ene- 
mies, and they show that they know this by their 
conduct. 
When a bird is the color of dead leaves, or 
