On the Normal and Abnormal Development of the Feather

A brief résumé is given of previous views of feather development. It is here emphasized that the collar is not to be regarded as producing a feather, but that it is in its entirety transformed into a feather and so is lost each time a feather is plucked. The culture of collar fragments is described. Many cultures produced apparently normal barbs and barbules without any process resembling concrescence. It is concluded that the only movement of...