Chapter 1636
[←1624]
Those who with Hæckel regard the gill-clefts with their attendant phenomena as illustrative of an active function in our amphibian and piscine ancestors (see his twelfth and thirteenth stages), ought to explain why the “vegetable with leaflets” (Prof. André Lefèvre) represented in fœtal growth, does not appear in his twenty-two stages through which the Monera have passed in their ascent to Man. Hæckel does not postulate a vegetable ancestor. The embryological argument is thus a two-edged sword and here cuts its possessor.