Work on both neuroembryology and the creeper mutant brought to Hamburger’s attention that there were no standardized morphological descriptions of normal chick development against which experimental animals could be compared. There was only Lillie’s study based on time (in hours) of incubation, which could, of course, be highly variable. This realization led Hamburger to work with Howard Hamilton to create a normal table for chicken development. In 1951, they published the table and stage descriptions that made possible standardized research on chick development and laid the foundation for use of the chick as the new model organism for embryology. (See Figure showing photos of the various stages).
Allen, Garland, Dletrich, Michael, Huber, Florian. 2016. "Victor Hamburger and Experimental Embryology." MBL History Project digital exhibit. http://history.archives.mbl.edu/exploring/exhibits/viktor-hamburger-and-experimental-embryology