SECRETING GLANDS. 39 
form red bloodcells. These pulp cords are joined to the Malpighian 
bodies and infiltrated arterial sheaths and to the connective-tissue 
septa. 
What are the cavernous veins of the spleen ? 
They are the terminations of the splenic veins. Their walls are 
made up of branching circular or oblique fibres upon which, here and 
there, lie endothelial cells of different shapes. The walls of these veins 
are therefore fenestrated, and are in direct communication with spaces 
in the pulp cords. 
What is the course of the blood in the spleen ? 
It is supposed after entering the Malpighian nodules to pass through 
them and enter the spaces in the pulp cords, which are not distinctly 
walled channels. Then, after circulating around the cells in the cords, 
it finally finds its way through the fenestrated walls of the cavernous 
veins and passes out at the hilum by the large efferent vein. 
SECRETING GLANDS. 
What is the general structure of a secreting gland ? 
It consists of a layer of epithelium arranged upon a delicate struct- 
ure or basement membrane, under which there is a layer of finely 
ramifying bloodvessels. Sometimes the basement membrane is absent. 
How may the extent of a secreting surface be increased ? 
By a protrusion of the secreting surface into simple or compound 
papillee, or by a recession of this surface in the form of tubules or 
saccules, simple or compound. 
What is the arrangement or plan of a compound gland ? 
The sides of a tubule become sacculated, or the tubule itself may 
branch. 
What is a racemose gland ? 
It is a gland composed of many alveoli, opening in clusters into the 
extremities of a branched tube or excretory duct. 
What is the arrangement of a compound tubular gland ? 
The gland tubules divide again and again into branches which retain 
their tubular character. The kidney is an example of this type of 
gland, 
