LOLIGO PEALII LESUEUR 255 



21. With a razor cut into the head in the median line between 

 the eyes both above and below the buccal bulb without injuring 

 the latter. Carefully remove the entire alimentary canal with 

 its glands, allowing it to float in water on one side. Make a 

 drawing showing the buccal bulb with the upper and lower 

 jaw, the anterior aorta and the oesophagus with the liver through 

 which they pass; the stomach, characterized by its thick mus- 

 cular walls; the thin and large stomach pouch; the short in- 

 testine passing between the two lobes of the pancreas and the 

 rectum with the rectal papillae. Show also the two hepatic ducts 

 connecting the liver with the pancreas and, if possible, the 

 hepato-pancreatic ducts; the median salivary gland which ap- 

 pears as a small white body imbedded in the liver on its anterior 

 upper surface. 



22. Open the buccal bulb and remove the radula. Place it 

 in a drop of glycerine on a slide under cover. Examine under 

 low power and make a drawing showing the arrangement and 

 shape of the teeth. 



23. (This exercise should take the place of the two preceding 

 ones, if the first specimen dissected was a male. In case the 

 first specimen was a female this exercise should take the place 

 of the fourteenth and fifteenth.) Cut off the head. Divide it 

 in two by a quick cut with a sharp razor along the plane of sym- 

 metry. Examine the cut surface of the left half. Compare it 

 with the text figure and make a drawing showing the cerebral, 

 pedal, visceral and propedal ganglia; the cephalic cartilage; the 

 buccal bulb with the upper and lower jaw and odontophore 

 (ligula and radula). 



24. Additional exercise. Open the mantle cavity of the in- 

 jected specimen as in paragraph 8. Remove all organs except 

 the gills and genital organs without disturbing or injuring the 

 blood-vessels. The liver has to be removed bit by bit to prevent 

 the breaking of the aorta. When the circulatory system is 

 completely exposed make a drawing of it in color. 



