FIGURES 2.396 TO 2.398. URINARY ORGANS OF OX-EMBRYOS.

FIGURE 2.399. SEXUAL ORGANS OF WATER-MOLE.

FIGURES 2.400 AND 2.401. ORIGINAL POSITION OF SEXUAL GLANDS.

FIGURE 2.402. UROGENITAL SYSTEM OF HUMAN EMBRYO.

FIGURE 2.403. SECTION OF OVARY.

FIGURES 2.404 TO 2.406. GRAAFIAN FOLLICLES.

FIGURE 2.407. A RIPE GRAAFIAN FOLLICLE.

FIGURE 2.408. THE HUMAN OVUM.




CHAPTER 2.16. STRUCTURE OF THE LANCELET AND THE SEA-SQUIRT.

In turning from the embryology to the phylogeny of man--from the
development of the individual to that of the species--we must bear in
mind the direct causal connection that exists between these two main
branches of the science of human evolution. This important causal
nexus finds its simplest expression in "the fundamental law of organic
development," the content and purport of which we have fully
considered in the first chapter. According to this biogenetic law,
ontogeny is a brief and condensed recapitulation of phylogeny. If this