DETERMINATION OF A.GE IN HONEY-BEES. 201 



filled with fluid. In crayfish and other animals which live 

 for some years with intervening periods of rest one would 

 expect to find alternating signs of fatigue aud recuperation 

 in the cells such as he describes. In bees, as far as can be 

 ascertained/ there is no nocturnal rest. The specimens for 

 experiment were^ however, taken from the hive about noon. 

 In this way it was hoped to eliminate any differences 'which 

 might possibly arise from daily fatigue. It seems very 

 doubtful, however, in spite of Hodge's results (9), whether 

 there is any recuperation during the night. Except that bees 

 do not fly after dusk, the various activities appear to go on 

 as usual. Certainly wax secretion and building of comb, 

 transference of honey or sugar from one part of the hive to 

 another, ventilating, guarding, etc., are carried on throughout 

 the night. It would be most surprising to obtain constant 

 differences in the nerve-cells of bees caught on the wing in 

 the morning and evening without taking their age inti> 

 account as first attempted by Hodge. 



Dolley (4) has shown that incessant exercise has a very 

 decided effect on the nerve-cells of artificially stimulated 

 dogs as well as of the crayfish as described above. One is 

 therefore not surprised to find that the incessant work done 

 by a bee produces a pronounced cumulative effect, and 

 further, since the bees normally work themselves to death in 

 so few weeks, that the condition of the nerve-cell gives a 

 good indication of age in bees. 



During successful hibernation no doubt a certain amount of 

 repair takes place in the brain and other tissues of the bee. 

 I hope to study these recuperation stages in more detail 

 during the winter. 



Some bees which appear to be dying of disease have been 

 found to have nerve-cells rather'less aged than those of the 

 active forager shown in PI. 11, fig. 7. It seems likely that 

 loss of activity consequent on attack by disease would prevent, 

 if anything, the usual disintegration of the nerve-ceils, so that 

 a diseased bee would appear, if studied from this point of 

 view, to be younger than it really is. 



