On the earliest blood‐vessels in the anterior limb buds of birds and their relation to the primary subclavian artery

Abstract

Our knowledge of the origin and method of formation of the vascular system in vertebrate embryos is still far from satisfactory, and, indeed, in many instances surprisingly inadequate.This is true, too, in spite of a long series of observations and a number of important contributions i n this field.We owe much, for instance, to Rathke, whose classical paper on the aortic arches and the vessels derived from them, dates from 1857, and to Hochstetkr, whose persistent labors have yielded such a wealth of facts on the development of various vessels.But the knowledge which these-and other researches have given us consists chiefly in an idea of the position and connections of the *A portion of the observations recorded in this paper were made while occupying one of the research rooms endowed by The Wistar Institute of Anatomy at the Marine Biological Laboratory, Woods Hole, Mass.I would acknowledge here my obligations and