CONTRIBUTIONS TO EMBRYOLOGY, No. 36. 



STUDIES ON THE ORIGIN OF BLOOD-VESSELS AND OF RED 



BLOOD-CORPUSCLES AS SEEN IN THE LIVING BLASTODERM 



OF CHICKS DURING THE SECOND DAY OF INCUBATION, 



BY FLORENCE R. SABIN, 



Professor of Histology in the Johns Hopkins University. 



With six plates and one text-figure. 



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