Chapter XII: The Region of the Spinal Cord

Difference between cranial and spinal regions--Absence of lateral
root--Meristic variation--Segmentation of coelom--Segmental
excretory organs--Development of nephric organs; pronephric,
mesonephric, metanephric--Excretory organs of Amphioxus--
Solenocytes--Excretory organs of Branchipus and Peripatus,
appendicular and somatic--Comparison of coelom of Peripatus and
of vertebrate--Pronephric organs compared to coxal glands--Origin
of vertebrate body-cavity (metacoele)--Segmental duct--Summary of
formation of excretory organs--Origin of somatic trunk-musculature--
Atrial cavity of Amphioxus--Pleural folds--Ventral growth of
pleural folds and somatic musculature--Pleural folds of
Cephalaspidæ and of Trilobita--Meaning of the ductless glands--
Alteration in structure of excretory organs which have lost their
duct in vertebrates and in invertebrates--Formation of lymphatic
glands--Segmental coxal glands of arthropods and of vertebrates--
Origin of adrenals, pituitary body, thymus, tonsils, thyroid, and
other ductless glands--Summary 385