358 DWIGHT E. MINNICH 



to the nearer | of a circumference, no attempt being made to 

 discriminate differences of less than 45°. In this record it is 

 desirable to combine both trails into a single computation. Pro- 

 ceeding as before, 



^ (+1 + 1-1-1) 360° 



D = /io OK 1 T 1 \~a~ = ~ 1-16°/ cm. 



(12.25 + 7.1 cm.) 6 ' 



The negative sign of the average deflection here obviously indi- 

 cates that the bee turned more toward the covered eye than 

 toward the functional eye in these trials. 



In the course of experimentation, records of normal bees were 

 also made in non-directive light. Since in such individuals neither 

 eye was blackened, the positive sign was arbitrarily applied to the 

 direction of greater angular deflection in each set of trials. Other- 

 wise the computations for normal bees were performed in the" 

 same manner as those for bees with one eye blackened. 



These various examples will illustrate the method employed in 

 all quantitative determinations. Upon the results thus obtained 

 the chief conclusions of the present paper are based. 



IV. MATERIAL 

 1. General care of animals 



The bees used in all quantitative experiments were thoroughly 

 active workers taken from the flowers of a near-by garden, and 

 were, for the most part, individuals from a single large hive situ- 

 ated there. The animals were trapped by simply inverting a 

 long glass tumbler over the flower, and then transferring them 

 to a small screen fly-trap. In some experiments, however, which 

 were performed too late in the fall to obtain bees in this way, 

 animals were used from a single comb of workers confined in an 

 observation hive. The exit of the hive was kept securely screened, 

 for such a colony quickly disintegrates if its members are per- 

 mitted to leave the hive freely. Bees kept in this way remained 

 in reasonably good condition, for at least a month. 



Bees destined to undergo experimentation were first subjected 

 to having their wings clipped, an operation easily executed when 



