THE LUNGS. 59 



centra between them, and from a small neigh- 

 boring area of the costal plates. From these 

 attachments the fibres spread out on all sides 

 to invest the lung. 



150. Cut through the bronchus, and entirely remove 

 the lung. Inflate it from the bronchus, and keep it 

 distended by tying the latter ; then hang it up for a 

 day or two to dry. When dry divide it into a dorsal 

 and ventral half, and observe its internal structure. 

 Note: 



a. That the bronchus is continued by a large tube 

 running to the posterior end of the lung, but 

 having no cartilages in its walls, except for a 

 very short distance near its commencement. 



b. That from this main bronchial tiibe^ others di- 

 verge at right angles to its general direction, 

 and end in incompletely separated air-cells, 

 which are much smaller in the anterior than 

 in the posterior portion of the lung. 



151. Trace the (Esophagus up to the mouth, and, pass- 

 ing a probe down from the latter, note the great disten- 

 sibility of the upper part of the gullet. Then remove 

 stomach and oesophagus, and, opening them, note the 

 folded mucous membrane lining them ; the rugcs being 

 most conspicuous in the stomach. 



152. Remove carefully the remaining lung, the liver, 

 and the genito-urinary organs, taking care not to in- 

 jure the dorsal spinal nerves, which are seen running 

 out across the interior of the carapace ; then clean the 

 great Retractor Muscles of the Head and Neck, of which 



