No. 2. J CHANGES IN NERVE CELLS. 155 



selves in the air for the short space necessary to regain the hive. 

 With food and parentage and every element of living so exactly 

 alike, observations like the above have led me to think that the 

 only difference between the bees in a hive, a difference which 

 might bring about a complication of results like that occurring 

 in Table XI, must be a difference of age. This would naturally 

 lead to a difference of work. 



Figs. II and 10 (PI. VIII) are drawn respectively from 

 bees 3 and 4. Although paired together by accident, they 

 serve to illustrate my point better than any of the others. In 

 No. 3, Fig. II, we notice that in cells of about the same size 

 the size of the nuclei varies considerably, and a good many 

 appear shrunken and somewhat angular in outline. In all the 

 other morning bees they are more uniform. Is it not possible 

 that this is the case of an old bee, in which the balance 

 between repair and waste has turned toward the side of waste .-' 

 The night's rest is no longer sufficient for complete recovery 

 from loss due to the day's work. Bee No. 4 (Fig. 10) is the 

 extreme case in the series. In no other one are the nuclei 

 quite so shrunken and the cell protoplasm so extremely vacuo- 

 lated. I cannot do less than make the remark regarding this 

 bee, that possibly it might have fallen by the hive to die that 

 night. 



Bee No. 12 is an evening bee that shows, so far as brain cells 

 or actions go, no signs of fatigue. If I were given a section 

 of any of the other bees' brains and asked : " Morning or 

 night .'' " I could tell which. With this one I should say, 

 "Morning." In strictest logic, therefore, I am obliged to say, 

 that in five cases out of six the cells of bees' brains show, 

 at night, effects of the day's fatigue. In one case in six 

 this does not appear. My own supposition, however, is that 

 No. 12 is a young bee, out for a stroll in the cool of the even- 

 ing. ^ 



The antennal lobes were chosen for special study, because 

 the cells were uniform in size, shape, and grouping, and were 

 easily located so that certainty of comparing similar parts was 

 attained. Other regions presented similar appearances, but 



^ The writer's regret for neglecting to observe " age signs " in the above bees 

 can better be imagined than expressed. However, experiments are under way to 

 remedy this defect. 



