1928] 
The Working Hours of Ants 
115 
and up the maple tree. Slight showers were found to have no 
effect upon the ants’ labor as they retreated to cover only during 
heavy, washing rains. When retreating, the food-bearers pro- 
ceeded back to the nest and the majority of those that were 
outward-bound congregated at the end of the dry limit of the 
route. As soon as the rain abated they resumed activity. 
During their wait they did not rest, but moved about con- 
tinually in the dry area. 
July 23 (6 a. m.) — There appeared to be as many individuals 
in the line as ever, but the speed seemed a trifle slower, and a few 
individuals were loitering an inch or two outside the working- 
line. At 8 a. m. the line appeared to be going full speed; at 2 
p. m., the same, except a half-dozen loitering in a fleck of sun- 
shine (cool temperature had prevailed for some hours). The 
loiterers were never entirely still, however, frequently moving 
about in a small area. At 9 p. m. the line was as strong and 
rapid as ever, except where snails were crossing the route, which 
caused some ants to stop and feed on their slime. 
July 24 (6. a. m.) — The line going full force; at 10 a. m. it 
was a little straggly. Weather sunshiny except that part of the 
course leading up the tree. At 5 p. m., the line unusually strong 
and more sand than usual being carried up. 
No more observations were made at Durham until 21 days 
later. On August 14 (4:30 p. m.) the line was found to be as 
strong in numbers and movement as on the previous dates. At 
8 p. m. the line was thicker than previously observed, and it 
was estimated to contain twice as many ants as it had contained 
at its lowest ebb. Instead of moving in single file, the line was 
five or six individuals deep in places. At 8:30 p. m. the marching 
ants appeared no less numerous. On August 15 (2 a. m.) there 
was still no diminution apparent. The weather at that hour 
was foggy, with diffused moonlight. On August 16 (6:30 a. m.) 
the line appeared to be moving at approximately half the strength 
of the night preceding. The weather was cloudy. On August 
17 (daybreak) the line was moving in full strength. 
No more observations were made this particular colony 
until some two weeks later. In the meanwhile, suspecting that 
