“…So far as we know, however, no report has come to definite conclusion about why some different kinds of tissues show the same inductive effect and, on the other hand, the same kinds of tissues of different animals are different in their inductive effects. Some investigators have tried to have an answer for this question by comparing the inductive effects of a tissue from well-fed and starved animals (5,27,30), and young and adult ones (14,19,20,26,30), but they refrained from giving any definite opinion on the question.…”