It has often occurred to me that conditions other than the toxins producing lactic acid were instrumental in decay of the teeth. This and interstitial gingivitis result from a struggle for assimilable nutriment dependent upon the action of the nervous system, operating through the law of economy of growth.
Elsewhere I have demonstrated the relation of degeneracy to the struggle for existence between the face and brain, the jaws and brain, the alveolar process and the jaws and face. I shall now discuss degeneracy of the teeth and their pulps, in relation to evolution.
In its evolution every structure in the body passes through embryologic phases1 resembling types found in the lower vertebrates. In such evolution it is affected beneficially by both degeneracy or the suppressive phase of evolution and the advance phase. These phases constitute a struggle for existence for assimilable nutriment which proceeds under the law of