86 ANATOMY OF A CHELONIAN. 



ing to sex). Do not make the dissections of the kidneys 

 or of the veins running to them, or of the inferior cava, 

 as these parts are alike in both sexes and the sympa- 

 thetic is apt to be injured in examining them. 



212. Dissect out the Sympathetic Chain on one side. 

 Find the main cord in the neck, where it separates from 

 the pneumogastric (99). Following it, it will be seen 

 to pass outward and backward, and to have on it a 

 large ganglion (middle cervical), from which several 

 branches proceed. One of them is larger than the rest, 

 and forms obviously the backward continuation of the 

 main trunk ; it proceeds toward the axilla. Amputate 

 the fore limb at the middle of the humerus, and care- 

 fully expose the brachial plexus. The sympathetic 

 cord runs toward this, and, before reaching it, presents 

 a third small ganglion (inferior cervical) ; crossing the 

 plexus it then enters a large fusiform ganglion (gan- 

 glion stellatum) placed on the ventral side of the most 

 posterior of the main trunks of the brachial plexus. 



213. Apparently proceeding from the ganglion is a 

 small nerve, which runs to the ventral aspect of the 

 lung and there ends in the muscular layer covering 

 this organ. The nerve probably gets filaments from 

 the ganglion, but careful dissection will show that it is 

 mainly derived from the trunk of the brachial plexus 

 on which the ganglion lies. 



214. From the posterior end of the ganglion stellatum 

 two filaments run back, one on each side of the sub- 

 clavian artery. They enter a ganglion which lies just 

 anterior to the first dorsal nerve, and is connected with 



