MOLLXTSCA. 73 



Place a slug (" a snail without a shell ") in a 

 horizontal position on a glass plate, being careful 

 that the plate is at right angles to the light. 



1. Observe and record by sketches the position of the 



snail at the end of 5, 10 and 15 minutes. 



2. Is the snail influenced in its movements by gravity? 



F, Phototaxis. The movements of animals or plants 



with reference to light is called phototaxis. 

 Have the glass plate used in E now stand with the 

 edge toward the light. Place the snail in a verti- 

 cal position. 



1. Observe and record by sketches the position of the 



snail at the end of 5, 10 and 15 minutes. 



2. Is the snail affected by light? How do you know? 



G. Eggs. 



These are often found in masses on the side of the 

 aquarium. 



1. Identify them. 



2. Examine with 1. and l.p. 



3. THE SQUID. 

 A. General Observations. 



Identify, — 



(1) the body; 



(2) the head ; 



(3) the eyes ; 



(4) the tentacles ; 



(5) the neck, that part which allows the head to 



move ; 



(6) the mantle, fitting like a collar around the neck ; 



(7) the siphon tube, showing between the collar and 



the neck on the ventral side ; 



