The first stage corresponds to the process of organization, the gelatine representing the blastema, and the drop the nucleus.
My first doubts of the blastema doctrine date from my researches on tubercle.
1849, Modern Latin, from Greek blastema "offspring, offshoot," from stem of blastanein "to shoot forth," from blastos "sprout, germ," of unknown origin. Related: Blastemal.
blastema blas·te·ma (blā-stē'mə)
The formative, undifferentiated material from which cells are formed.
A mass of embryonic cells from which an organ or a body part develops, either in normal development or in the regeneration of a lost body part.