292 
DARWINISM 
CHAP. 
springs from a very small area on the side of the breast. Mr. 
Frank E. Beddard, who has kindly examined a specimen for 
me, says that “ this area lies upon the pectoral muscles, and 
near to the point where the fibres of the muscle converge 
towards their attachment to the humerus. The plumes arise, 
therefore, close to the most powerful muscle of the body, and 
near to where the activities of that muscle would be at a 
maximum. Furthermore, the area of attachment of the plumes 
is just above the point where the arteries and nerves for the 
supply of the pectoral muscles, and neighbouring regions, 
leave the interior of the body. The area of attachment of 
the plume is, also, as you say in your letter, just above the 
junction of the coracoid and sternum.” Ornamental plumes 
of considerable size rise from the same part in many other 
species of paradise birds, sometimes extending laterally in front, 
so as to form breast shields. They also occur in many humming¬ 
birds, and in some sun-birds and honey-suckers; and in all these 
cases there is a wonderful amount of activity and rapid move¬ 
ment, indicating a surplus of vitality, which is able to manifest 
itself in the development of these accessory plumes. 1 
In a quite distinct set of birds, the gallinacese, we find the 
ornamental plumage usually arising from very different parts, in 
the form of elongated tail-feathers or tail-coverts, and of ruffs 
or hackles from the neck. Here the wings are comparatively 
little used, the most constant activities depending on the legs, 
since the gallinacese are pre-eminently walking, running, and 
scratching birds. Now the magnificent train of the peacock 
—the grandest development of accessory plumes in this order 
—springs from an oval or circular area, about three inches in 
diameter, just above the base of the tail, and, therefore, 
situated over the lower part of the spinal column near the 
insertion of the powerful muscles which move the hind limbs 
and elevate the tail. The very frequent presence of neck-ruffs 
or breast-shields in the males of birds with accessory plumes 
may be partly due to selection, because they must serve as a 
protection in their mutual combats, just as does the lion’s or the 
horse’s mane. The enormously lengthened plumes of the bird 
of paradise and of the peacock can, however, have no such use, 
1 For activity and pugnacity of humming-birds, see Tropical Nature, pp. 
130, 213. 
