LOLIGO 



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ganglion, which is supposed to represent the fused pedal and 

 visceral ganglia and (together with the masses that connect 

 the supra- and infra-esophageal ganglia around the esoph- 

 agus) the pleural ganglia. 



3. The anterior prolongation of the infra-esophageal gang- 

 lion to form the propedal portion, which supplies nerves to 



the arms. 



4. The small suprabuccal ganglia, lying dorsal to the 

 esophagus, and a little further anterior than the ends of the 

 propedal portion. These are joined by connectives with the 

 supra-esophageal ganglia. 



5. The infrabuccal ganglia, about the same size as, and 

 lying ventral to, the suprabuccal ganglia, and joined with 

 them by connectives that run around the esophagus. 



Draw a figure of a sagittal section of the head. 



Two large ganglia, the optic ganglia, lie against the eyes 

 and will be seen in cross sections of the head that will be 

 studied later. A dissection of one side of the head will show 



one. 



Open the animal along the mid-dorsal line and find the pen 

 which is embedded in the mantle. After exposing it for its 

 full length, turn the flaps aside and see that it lies in a pocket. 

 It probably represents a modified shell that has become en- 

 tirely inclosed by the mantle. What is its function? 



Pull the pen out of the mantle and draw it. 



With a razor make cross sections of a squid, a quarter of 

 an inch thick, and arrange them in order, in a little water, as 

 they are made. Identify the parts you have found in dissec- 

 tion. 



Make drawings of the sections that pass through the infra- 

 esophageal ganglion, through the eyes, through the liver, and 

 through the heart. 



If time permits, study prepared sections that have pre- 

 viously been made. The structure of the eye and the posi- 

 tions of the parts of the nervous system should receive special 

 attention. 



