NERVOUS SYSTEM. IO3 



the head, neck, thorax and right anterior hmb. Begins at the 

 first himbar vertebra as a cistern, the " receptaculum chyli'' The 

 duct then passes forward through the pillars of the diaphragm to 

 the sixth ^^n^r/ vertebra, where it passes to the left and empties, 

 after a dilatation, into the anterior cava at the junction of the 

 the jugulars. 



RIGHT LYMPHATIC DUCT. 



Opens at junction of jugulars and is guarded by a valve. It is 

 about two inches long and receives all the lymphatics that do not 

 empty into the great duct. 



NERVOUS SYSTEM. 



This system is divided into the cereb7'o- spinal, presiding over 

 animal life, and sympathetic, over organic life. 



It is composed of white fibres, gray vesicles in a stroma of 

 neitrolgia or connective tissue, and a gelaiijioiis material in the 

 sympathetic. 



The white nervous tissue is composed of an outer envelope or 

 tubular membraiie, a middle coat called the white substance of 

 Schwann, and a central portion which transmits nervous im.pulses, 

 the axis cylinder. Outside a ;/<?rz'<f which comprises a number of 

 the preceding we find a covering, the 7ieurilenuna : sensory nerves 

 terminate at the periphery in many different ways, motor nerves 

 as small plexuses on the muscle cells. 



CEREBRO-SPINAL SYSTEM. 

 Consists of the brain, spinal cord, ganglia and nerves. 



SPINAL CORD. 



The portion of the nervous system enclosed in the spinal canal 

 and extending from the occipital foramen to the upper third of the 

 spinal canal. Its weight is lo^ ounces ; it is flattened above and 

 below, and has two enlargements in its course, one between the 

 fifth cervical and second dorsal, the bi'achial, the other below, the 

 crural. 



The structure is externally white matter, internally gray, ar- 

 ranged like two horns, the larger ends pointing down and out, not 



