18y().J MICROSCOPICAL JOURNAL. 421 



cover and examine (high power) note the cross markings 

 striatious the whole length of the fibre; note also that the 

 fibres in some case» tend to divide up into lesser slender 

 fibrillae in the length of the fibre. 



[13. The Nervous System.— The general plan of the 

 nervous system is that of the vertebrates at large, viz: — 

 {\) central system con^\&i\ng of: 'ji brain; a. spinal cord; 

 and the sympathetic system; and (2) the peripheral sy stein 

 consisting of the serial cranial and spinal nerves and the 

 nerve-fibres of tlie sympathetic system. The brain has 

 alread}' been dissected, the spinal cord can be seen by 

 cutting away the neural arches (see section 14) of the 

 vertebrae; the spinal nerves can be seen in the body wall 

 beside the ribs in places; the sympathetic system can 

 hardly be seen by a beginner, it consists of a chain of 

 ganglia lying in the trunk region in the dorsal wall of 

 the body cavity covered by the peritoneum; fibres from 

 it communicate with the spinal cord and with the various 

 viscera. The cerebro-spinal system in general is related 

 to the sensations and voluntary motions of the animal 

 while the sympathetic system is used in controlling the 

 viscera (vegetative life).] 



14. The Skeleton of the Trunk. — Using a fish that 

 has been well boiled so as to loosen the muscular tissue 

 from the bones, remove carefully as much as possible of 

 the flesh, leaving the bones Including the ribs iu position 

 as far as you can. Be especially careful not to detach 

 the caudal fin. After you have removed all the flesh 

 wash the skeleton and dry it. It is a help in keeping 

 the bones together to have the back-bone lying on a piece 

 of paper on which it is kept while being washed and 

 dried. If it is later desired to separate particular bones 

 for study they can easily be soaked with warm water and 

 removed. 



