1928] 
The Working Hours of Ants 
117 
would go on with no more than a slight touch, apparently res- 
pecting the siesta hour of its comrade. 
On September 3 (10:30 a. m.) the traffic was even lighter, so 
that not more than twenty ants could be counted at work in the 
whole procession. This was by far the largest falling off in 
workers observed during the entire summer, either by day or 
night At this time seven sleepers were counted along the line, 
the remainder of the workers, whether asleep or awake, evidently 
being in the nest. On September 4, with warmer temperature, 
the line was again moving in full force. With lowering tempera- 
ture the work gradually slowed down until on September 24, at 
sunrise, only one benumbed individual was out and at 7. a. m. 
(temperature 50) for the first time since the beginning of my 
observation in July, not a single individual was to be seen. On 
October 15, at noon, (temperature 59) six were out but moving 
slowly. This was the last appearance noted for the autumn. 
In the spring of 1928 observations were made on the re- 
sumption of work by this colony. March 29, 6:00 p. m. (tem- 
perature 78) thirty-five individuals were seen to be following their 
old route. As the earth portion of the trail had been spaded 
under, it would appear that the ants followed the old route from 
memory and not as an odor-path. They followed exactly the 
same course up the tree but carried no building material, and by 
their movements appeared to be scouting. Until May 22, the 
last date of observation, the line continued to move steadily along 
the old trail except in very cold weather; and on the above date 
I observed that a few individuals were carrying sand up the tree, 
though apparently without any definite purpose, and as if they 
were merely acting upon a recollection of last season’s activities. 
It is realized that the foregoing observations are fragmentary 
and it is hoped that other observers will make a more extensive 
study of the subject. However, I shall venture to make a few 
surmises, rather than conclusions, from the limited data secured. 
The foregoing observations lead me to believe: 
1. That excitement, caused by such circumstances as the 
discovery of aphids, or perhaps the building of a new nest, or 
