274 W. C. ALLEE 



dred young were taken from a single brood pouch. More than 

 one brood is brought forth by the same female in one season. 

 Some of the animals may live over another winter although many 

 of them die off at the close of the breeding season. In nature the 

 breeding habitat is restricted to the most favorable locations. 

 Banta did no work with animals during the breeding season. 



2. The food of A. communis as determined both by observing 

 their feeding habits and by examining their alimentary tract, 

 consists of algae, larger green water plants, protozoa, decaying 

 leaves and dead animals. 



3. They are strongly positive to gravity and water pressure 

 when these are acting alone but if light is introduced the reaction 

 is controlled by the light. 



4. A. communis is strongly positive to tactile stimuli. The 

 hairs are sensitive to touch so that a response is given , even when 

 antennae, antennules, and uropods are removed. The positive 

 thigmotaxis is shown by their tendency to collect in corners or 

 under thin mica plates. Again if subjected to the action of light 

 they will disregard their thigmotactic optimum and respond to 

 light alone. 



5. Their temperature optimum varies, depending on the tem- 

 perature in which they have been kept. Sudden temperature 

 changes in either direction cause them to collect in bunches, more 

 extreme changes cause the 'pill bug' reaction and if these condi- 

 tions continue death results. 



6. A. communis is negative to direct sunlight or to a large 

 amount of diffuse light although they are positive to room light 

 admitted through a very small opening. Young animals are 

 negative to all light intensities used. The adults have a light opti- 

 mum, as this shifts they change their position until they are in 

 optimum conditions. The response to light is affected by their 

 previous exposure. Banta ('10, pp. 263-269) found in this con- 

 nection that after being in darkness for several hours Asellus is 

 positive to all light intensities tried, the duration of the positive 

 response depending on the intensity of the light. In my experi- 

 ments however they were most positive to faint light after forty 

 hours continuous exposure to a light intensity of 80 candle 



