Fnrther Observations on Koeneuia. 409 



me tliat Koenenia made to react to these strong- geotropic and stereo- 

 tropic Stimuli iieed not necessarily always be found under stones it 

 tlie soil presented tlie proper hydrotropic Stimuli. These animals 

 undeniably leave tlie stones and go down tliroug-li the soil Avhen tlie 

 groimd becomes dry on the surface. I had never found them under 

 these conditions. however. until the morning- of May 13th. We had 

 been having good rains about Austin and the moisture seemed 

 equally distributed throughout the surface to a depth of several feet. 

 I Avas expecting to find a great number of specimens and was dis- 

 appointed on taking up stones to find nothing. On dig-ging up a 

 small trowel of dirt at randoni, I was surprised and delighted to see 

 two of the little animals moving swiftly and gracefully around through 

 the soil. Following this plan of searching we succeeded in a short 

 time in capturing thirty-seven specimens; of these only five came 

 from under the stones. For the few days that this small area was 

 blessed with moisture Koenenia were found in the soil. 



That the animals are attected b}" the rains and also by another 

 Stimulus due either to heat or to the conditions of the sexual organs 

 at certain periods, the following table will show. The table was at 

 first arranged to give the sexes so far as they could be determined 

 when the animals were examined alive immediately after capture. 

 Offen the inales when alive contract their reproductive appendages 

 to a certain extent so that the striking contour. which they usually 

 present in dead specimens, was lost. When it became so evident 

 that the sexes always appeared together and when other forms 

 began to appear I ceased to record the number of each sex, and 

 gave my whole attention to the other forms. In all my collecting, 

 however where more than two specimens were obtained I never 

 failed but on one occasion to take individuals of both sexes, as the 

 table (page 410) will show. 



After the 19th day of May it again became too dry for collecting. 

 A few specimens might have been obtained where the ground was 

 not thoroughly dry but the heat was too great and the "red-bugs" 

 too numerous for field work. These periodic droughts for the last 

 two years have made a systematic collection for Information on the 

 life-history of Koenenia a hopeless task. That the appearance of 

 these animals on the surface does not depend on the rainfall alone 

 is shown from the fact that in April after a seveie rainstorm which 



in by a friead , who captured it on her dresser near a large window, at 

 8 A. M. behaved in the same wav. 



