The central part of the obstructed area very soon undergoes degenerative changes, and rapidly becomes decolourized.
The feathers of a peacock afford a convenient example of primitive and degenerative simplicity.
- In many pathological conditions we have degenerative products of various kinds formed in the tissues.
Certain peculiar substances, probably degenerative products, some of them reducing copper, are occasionally met with.
Degenerative simplicity is never uniformly distributed over all the structures of the organism.
Certain degenerative changes in the supra-renal glands may lead to Addison's disease, which is characterized by an excessive pigmentary condition of the skin and mucous membranes.
The one-sided specialization and the peculiar metallic colouring of the lateral tail feathers mark them as the extreme terms of a degenerative series, whilst the symmetry, likeness of constituent parts inter se, and absence of specialized pigment, as well as the fact that they differ little from any average feather of birds in general, mark the contour feather as primitively simple, and as the starting-point from which the highly elaborated eye-painted tail feather has gradually evolved.
When some time has elapsed before treatment and the phosphorus has become absorbed, the organic degenerative changes cannot be easily controlled.