Encyclopaedia Britannica, 11th Edition, "Ichthyology" to "Independence"

part in the formation of the packing tissue of the body. Much of this

forms the various kinds of connective tissue which fill up many of the spaces between the various epithelial layers; other and very important parts of the general mesenchyme become specialized in two definite directions and give rise to two special systems of organs. One of these is characterized by the fact that ...