Air cell gas tensions of the chick embryo at sea level and altitude: the contribution of Aggazzotti, 1914.

This historical note draws attention to the forgotten but remarkable study of A. Aggazzotti of Italy who in 1914 described for the first time the changes in O2 and CO2 tensions during the course of development of the chick embryo and repeated these observations at an altitude of 3000 m. When his gas tension data are recalculated and compared with those obtained by Wangensteen et al. at sea level and altitude, 60 years later, the agreement is good.