118 
Psyche 
[June 
some other general disturbance, seems to occasion an outburst of 
prolonged activity among ants, at least in some species. 
2. By the fact that the working line is considerably rein- 
forced or diminished at certain times, it is possible that ants 
may work in relays, so that one portion of the colony may be rest- 
ing in the nest while the other portion toils. Considering the fine 
point to which ants have developed their division of labor among 
various castes such a relay system could hardly be said to be 
beyond their powers. It may also be that ants require less rest 
than heavier animals, so that by a mere change in their rate of 
speed or by absorption of moisture or sunshine they receive 
renewed vitality. 
3. The Crematogaster is probably a common night-worker, 
at least in North Carolina. 
4. Formica pallide-fuiva probably prefers to work in the 
sunshine rather than at night. The fact that this species is 
largely a flesh-eater may have some bearing on the matter, as 
its prey may be more available in daylight hours. 
5. It is probable that temperature plays a large part in the 
working hours of ants. Just as an ant-colony suspends work 
above ground in winter, with the exception of infrequent jour- 
neys of occasional community foragers, it seems reasonable to 
suppose that any perceptible drop in temperature would lessen 
activity. Altitude, also, probably affects the work of ants. I 
attempted to make some observations in this regard at the 
summit of Mount Mitchell (6711 feet) during the summer, but 
was unable to find any ants at all, even during the day. It is 
probably too cold and high there, as none of the night-serenading 
insects ,such as katydids or crickets, were to be heard. 
