180 D WIGHT E. MINNICH 



tion and the absence of other strong, distracting stimuli are 

 necessary to its demonstration. The situation here differs 

 from that described by Loeb ('90) for winged male and female 

 ants, in which positive phototropism is confined exclusively to 

 the period of the nuptial flight. 



We may agree with Kellogg, therefore, that the issuance of 

 bees from the hive at swarming may be a simple exhibition of 

 positive phototropism, but it is not the result of a sudden increase 

 in phototropism. The sudden increase is in the activity of the 

 animals. Consequently, the fundamental factors in swarm 

 behavior are those which effect a condition of heightened ac- 

 tivity, a condition in which locomotion is generally controlled 

 by light. In my own observations the state of heightened activity 

 doubtless arose from the conditions of temperature and the pre- 

 vention of the bees from making their accustomed flights for 

 defecation, etc. The factors which activate the swarm are not 

 known. They may consist of particular swarm instincts, as 

 von Buttel-Reepen ('15) has suggested, or they may even be 

 more simple reflexes of as yet unknown nature. In any case, 

 the evidence seems clear that, although phototropism may be 

 an important feature of swarm behavior, it is neither peculiar 

 to this activity nor the primary causal agent of it. 



REFERENCES 



BUTTEL-REEPEN, H. VON 1915 Leben und Wesen der Bienen. Braunschweig, 



8vo, xiv + 300 pp. 

 GEABER, V. 1884 Grundlinien zur Erforschung des Helligkeits-und Farben- 



sinnes der Tiere. Prag und Leipzig, 8vo, viii + 322 pp. 

 HESS, C. 1913 a Gesichtssinn. Handb. vergl. Physiol. von Hans Winterstein, 



iv, 555-840. 

 HESS, C. 1913 b Experimentelle Untersuchungen iiber den angeblichen Farben- 



sinn der Bienen. Zool. Jahrb., xxxiv, Abt. allg. Zool. u. Physiol. der 



Tiere, 81-106. 

 HESS, C. 1917 New experiments on the light reactions of plants and animals. 



Jour. Animal Behavior, vii, 1-10. 



KELLOGG, V. L. 1903 Some insect reflexes. Science, N. S., xviii, 693-696. 

 LOEB, J. 1890 Der Heliotropismus der Thiere und seine Uebereinstimmung 



mit dem Heliotropismus der Pflanzen. Wiirzburg, 8vo, 118 pp. 

 LUBBOCK, J. 1882 Ants, bees and wasps. New York, 12mo, xix + 448 pp. 



