8 LIBBIE H. HYMAN AND ALBERT E, GALIGHER 



3. Material and inethod. The species used, Lumbriculus 

 inconstans Smith, was obtained from pools in the woods near the 

 village of Clarke, Indiana. These pools, filled with fallen leaves 

 and moss, are the characteristic habitat of this species. The 

 pools dry up in summer or fall, depending on their size, and when 

 this occurs the worms pass into an encysted state, emerging when 

 the pools become filled with water again in the spring. The 

 best time to collect the worms in numbers is when the pool has 

 dried down until only a small puddle of water is left in the lowest 

 part. In this puddle the worms collect in great numbers and may 

 be picked out by spreading out the debris from the pool on a 

 dry spot. The worms used in these experiments came from three 

 collections made on October 1st, 12th, and 15th, and from two 

 different pools. They were kept in the laboratory in dishes 

 of well-water filled with debris from their native pools and were 

 used within three weeks from the time of collection. 



The worms used were 40 to 60 mm. long and consisted of 150 

 to 200 segments. As many worms will be found regenerating 

 the tips of the tails it was not possible to avoid entirely using 

 such worms. Worms showing signs of regeneration elsewhere 

 than the tip of the tail were discarded. Three pieces were cut 

 out of each worm, as illustrated in figure 2. The head of the 

 worm was cut off and discarded and the first piece then cut 

 immediately behind the head. The second piece was cut im- 

 mediately posterior to the first one. The third piece was cut 

 near the posterior end, the extreme posterior end, including the 

 regenerating tip if such were present, being discarded. The first 

 two pieces were of equal length, being usually 3 to 5 mm. long 

 and containing ten to twelve segments. The posterior piece 

 was generally cut longer than the other two pieces, owing to the 

 smaller diameter of the posterior end, and was about 8 to 10 mm. 

 long, containing twenty to thirty segments. There was naturally 

 some variation in the length of the pieces corresponding to the 

 variation In the length of the worms from which the pieces were 

 cut. These pieces are too long to be stimulated by the cutting 

 except of course at the cut surfaces, where such stimulation always 

 occurs. However, as each piece possesses two cut surfaces, this 

 factor is equalized. 



