HYDROIDES, SPIRORBIS, LUMBRICUS 109 



SPIRORBIS 



This animal is also a member of the family Serpulidae. 

 Specimens are very abundant along the shore, attached to 

 Fucus. 



1. Study the tube and notice the way in which it "par- 

 allels" the form of a small snail shell. 



2. Remove a live specimen from the Fucus on which it 

 grows and crack the tube away with a needle. Study the 

 animal in a watch glass with a low power. Identify the aills, 

 the operculum (which serves as a "brood pouch"), the setae, 

 and the collar. Are any "eyes" on the gills? 



3. Study the egg strings which are lodged in the tube, and 

 the young embryos which are to be found in the brood pouch. 



A drawing is desirable. 



LUMBRICUS (Earthworm) 



Earthworms feed mostly at night. What reason is there 

 for this habit? You should look for earthworms with a lan- 

 tern some mild, calm summer evening when the ground is 

 quite moist. See if they leave their burrows entirely. How 

 much of the body is generally protruded? Can you deter- 

 mine what the worms are doing? Are they disturbed by 

 walking near them? Are they ever disturbed by flashing the 

 light suddenly upon them? Of what service to them is the 

 ability to distinguish light? Look for castings near the bur- 

 rows. During daylight look for castings and thus determine 

 the relative abundance of worms in lawns, gardens, etc. (As 

 the worms come to the surface only when it is moist, castings 

 will be abundant only at such times.) Do the casting in- 

 dicate anything about the feeding habits? 



Place a living specimen upon moist filter paper and ob- 

 serve the direction and method of movement. How can it 

 reverse its direction? Gently touch different parts of the 

 body to see which are the most sensitive. 



Observe the movement of the blood in the dorsal vessel. 

 In what direction does it move? Does the vessel change in 

 shape? 



