EXPERIMENTS ON CO-OPERATION. 371 



last she went round the outside of cup 1, instead of 

 going straight to the spot where I had placed the bit 

 of wood. 



On January 9 again I watched her under simi 

 lar circumstances. From 9.35 to 1.40 she made 55 

 journeys to and fro, carrying off a larva each time ; but 

 during this period only one other ant found the larvae. 



In the afternoon of the same day I watched the 

 ant which had been under observation on the 3rd Jan. 

 From 3.27 to 9.30 she made forty-two visits, during 

 which time only four other ants came to the larvae. 



On January 10 I watched the same ant as on the 

 4:th. Between 11 a.m. and 10 p.m. she made no less 

 than ninety-two visits ; and during the whole time only 

 one strange ant came to the larvae. 



On January 18 1 put out some more larvae in the 

 small porcelain cups. Between 8 and 9 both these ants 

 found them, and kept on coming all day up to 7 P.M., 

 when I left off observing. There were a good many 

 ants wandering about in the box; but up to 4 o'clock 

 only four came to the larvae. Two of them I impri- 

 soned as usual ; but two (which came at 4.30 and 4.36) 

 I marked. These went on working quietly with the 

 first two till I left off observing at 7 P.M. ; and during 

 this latter time only three other ants found the larvae. 



On January 31 I watched another specimen. At 

 9.14 I put her into a small cup containing a number of 

 larvae. She worked continuously till half-past seven in 

 the evening, when I left off watching. During that 

 time she had made more than ninety journeys, carrying 

 each time a larva to the nest. During the whole time 

 not asingle other ant came to the larvae. 



Again, on February 7, I watched two ants in the 

 same manner. At 7 A.M. I put some larvae in the small 

 china cups. Up to 8 no ants had come to them. Soon 

 after 8 I put two marked ants, neither of them being 

 the same as these whose movements are above recorded. 



