THE NERVOUS SYSTEM. 107 



I. THE SPINAL COKD SLIGHTLY MAGNIFIED. 



Study with a magnifying glass a microscopical slide of 

 a cross-section of a spinal cord. 



Notice : 



a. Its general shape. 



b. The anterior, ventral fissure is the deep indentation on 

 one side. 



c. The posterior, dorsal fissure is on the opposite side. 



d. The membranes around the cord. How many are there ? 



e. The white substance is just within the membranes. 

 Distinguish the anterior, lateral, and posterior columns. 



/. The gray substance is within the white substance. 

 What is its shape ? Find the anterior and posterior cornua. 



g. The canal is in the centre of the gray substance. 

 What is its size? 



h. The cerebro-spinal fluid was within the canal. 



i. The roots of the nerves. Which roots are they, the 

 anterior or the posterior? 



j. The blood-vessels. What is their relation to the septa 

 or extensions of the pia mater into the cord ? 



k. Sketch. 



II. THE SPINAL CORD HIGHLY MAGNIFIED. 



Study the section with the high power of the com- 

 pound microscope. 



Notice in the gray substance : 

 a. The nerve cells. 



1. The shape. 



2. The cell protoplasm. 



3. The nucleus. 



