BLOODVESSELS. 385 
break up into fine fibrils. In the finger ends we find them ending in 
peculiar oval bodies, made up of concentric lamelle and called Pacinian 
bodies. 
Describe the non-medullated nerve fibre. 
Non-medullated fibres, or fibres of Remak, are naked fibres having 
no medullary sheath and no neurilemma. They communicate by fre- 
quent branches and have on their surfaces flattened elongated nuclei at 
frequent intervals. They originate in peculiar cells, to be described 
later. As to their distribution little is known. 
Describe nerve cells. 
The cell-body is finely granular. They have a large, well-defined 
nucleus, usually showing a large, shining neucleolus. The cells branch 
and have one or more processes, and are called unipolar or multipolar 
ganglion cells, according to the number of processes. Some of these 
processes continue as nerve fibres while others break up into fine fibrils. 
The cells vary considerably as to size and shape. 
What is the peculiar point concerning ganglion cells of the sympa- 
thetic nervous system ? 
They are surrounded by a distinct capsule of connective tissue lined 
with flattened cells resembling endothelium. Through this capsule 
one or more cell processes pass to become non-medullated nerve fibres. 
THE CIRCULATORY SYSTEM. 
BLOODVESSELS. 
Name the varieties of bloodvessels. 
Arteries, veins and capillaries. 
What are the capillary bloodvessels ? 
They are simple tubes forming the connecting link between the 
arteries and veins. 
What is their structure ? 
The walls of a capillary vessel is composed of a single layer of endo- 
thelial cells joined together, edge to edge, by an intercellular cement 
substance. 
What is an arteriole ? 
It is the name applied to terminal arteries, and differs from a capil- 
lary in that its lumen is larger and it has, besides the layer of cells 
forming the inner coat, a layer of connective tissue forming the adven- 
