MOLGULA 235 



3. Ascertain the number of lobes at the extremity of each 

 siphon. Are pigment spots present on the siphonal lobes? 



Certain organs are distinguishable through the tough tunic 

 which incloses the body. The endostyle, a ciliated groove 

 looking like a white thread along the midventral line of the 

 pharynx or branchial basket, will serve as a guide in orient- 

 ing the animal. Determine dorsal, ventral, anterior, posterior, 

 right, and left aspects. 



Make a drawing of an expanded animal. 



4. The tunic or test can be removed by cutting through it 

 with scissors, taking care not to injure the mantle or body 

 wall. Enlarge the opening made in the tunic and strip it 

 from the body. Where is the tunic most firmly attached? 

 Examine a small piece of the tunic microscopically. Are 

 blood vessels visible in it? Does it contain any cells? 



5. For further study use both fresh and preserved material 

 from which the tunic has been removed. Identify as many 

 organs as possible through the mantle. In a living specimen 

 note the beating of the heart (the heart is on the right side) 

 and the frequent reversal of the direction of the pulsations. 

 The endostyle, longitudinal pharyngeal folds, intestine, gon- 

 ads, gonoducts, renal organ, and subneural glands are also 

 visible through the mantle. 



6. Note the muscle bands of the mantle which serve to 

 contract the body and especially the siphons. Where are 

 the muscles best developed? Is there any definite arrange- 

 ment of the muscle bands? 



Fix a large specimen by pins through the siphons, and 

 with scissors and fine forceps remove a large section of the 

 mantle from the left side, between the digestive tract and 

 the siphons, injuring the underlying pharynx as little as pos- 

 sible. The large space between the pharynx and the mantle, 

 laterally and dorsally, is the atrium, or peribranchial cham- 

 ber, which is formed as an ectodermal involution. Into this 



