Lumbricidae 195 



To feed tubificids the following materials have been used: fresh horse 

 manure, baked potatoes cut in halves, boiled potatoes, butts from head 

 lettuce, masses of bran, and bread. Press food down into the mud. The 

 horse manure and bran should be buried in the mud. 



The worms are removed in small masses by means of a pair of forceps. 

 Wash them to remove mud before feeding them to other animals. 



Reference 

 For the culture of Tubificidae see also p. 142. 



Family lumbricidae 



EARTHWORMS 



Walter N. Hess, Hamilton College 



SINCE living earthworms are useful in the laboratory for demon- 

 strating behavior, and since freshly killed earthworms are far 

 superior to preserved specimens for the study of certain organ systems, 

 especially the digestive, circulatory and excretory systems, many lab- 

 oratories need a supply of living worms for mid-winter use. Brief con- 

 sideration will be given to the culturing of three species. 



Specimens of Lumbricus terrestris, the common earthworm of the 

 United States, must be gathered at night and preferably between 10:00 

 and 12:00 o'clock during or following a drizzling, warm rain when the 

 ground is thoroughly soaked. The worms come to the surface of the 

 ground in large numbers at such times and may be captured easily with 

 the assistance of a strong flash light or an acetylene lantern. The best 

 collecting grounds are closely cut lawns where the soil is rich. 



When the worms have been collected they may be left for the re- 

 mainder of the night in a cool place in a pail containing a small quantity 

 of freshly cut grass. The next morning the worms should be carefully 

 sorted, and all injured or abnormal specimens should be removed. If 

 they are washed and placed, a few at a time, in a dish of water those that 

 are injured may easily be detected. 



Earthworms feed very largely on dead and decaying leaves and, like 

 chickens, they digest their food better if there is a certain amount of 

 grit in their diets. We have obtained best results by keeping earthworms 

 in large boxes filled about 1 2 inches deep with approximately equal parts 

 of old leaves and leaf loam gathered in the woods. Under no conditions 

 should heavy clay soil be used. The worms need no other food, as they 

 feed on the dead leaves. The material should be kept moist but not 

 saturated with water. Unless extreme care was exercised in removing 

 all injured worms, the boxes should be inspected after a week and all 



