XV] PERIPHERAL GANGLIA AND NERVE CELLS 121 



Scrape off the mucous membrane, and mount in formic 

 glycerine two pieces of the muscular coat, one with the outer, 

 the other with the inner surface uppermost. Note the wide- 

 meshed plexus of Auerbach between the muscular coats ; the 

 meshes are rectangular and groups of close-set small cells lie at 

 the nodal points, their nuclei staining less than the cell sub- 

 stance. The plexus of Meissner may be seen in places in the 

 sub-mucous layer; it is similar to that of Auerbach but the 

 meshes are irregular in shape, the strands and groups of nerve 

 cells smaller (cp. Less. xxi. 1, 6, e). 



10. Ganglia of the sympathetic chain in the frog. Lay open 

 the abdomen of a recently killed frog, raise the rectum, and 

 remove the intestine, liver and stomach, cutting through the 

 mesentery just above the kidneys. Lift up the kidnej'S and cut 

 between them. Lift up each kidney in turn, the peritoneum 

 separating the abdominal cavity from the lymphatica cisterna 

 magna will be seen stretching from the lateral edge of the 

 kidney to the body wall. Eemove the kidneys with this part of 

 the peritoneum. Sponge up any blood that may be present. 



Note on either side of the aorta a longitudinal pigmented 

 strand, the sympathetic chain, and the fine nerves the rami 

 communicantes connecting it with the adjacent spinal nerves. 

 With the aid of a lens, the ganglia may be seen as spindle-shaped 

 swellings on the sympathetic chain. 



Eemove the chain on one side ; stretch it out on a slide, 

 cover, and add normal salt solution. Examine with a high 

 power. Note the nearly globular, transparent nerve cells ; much 

 hidden by the pigment cells. The nerve fibres of the rami are 

 chiefly small medullated fibres. 



By treating the sympathetic chain with dilute methylene blue 

 as directed in Less. xvi. 1, a cell will here and there be seen 

 with deep blue spiral fibre and showing the branchings of the 

 spiral fibre (synapses) on the cell. 



