HARVESTING ANTS. 173 



kept the tube tiglitly corked for nine days, only once 

 removing the cork for a few seconds in order to 

 sprinkle a little water on the ants, which were evi- 

 dently in need of it. On the ninth da}^ I turned out 

 the contents of the tube and found that all the peas, 

 millet and cress, had germinated and were growing 

 strongly. One of the cress, however, had had its 

 root, which lay across the gallery constructed by 

 the ants, gnawed off; four clover seeds, which had 

 come with the soil taken from the nest, and which 

 had formed part of the ants' stores, had germinated 

 also. Here the small quantity of air contained 

 in the test-tube must certainly have become satu- 

 rated with any vapour which the ants may be sup- 

 posed to give off, and we cannot therefore accept this 

 as the cause of the dormant condition of the granary 

 seeds. 



I made other experiments in which harvesting ants 

 were imprisoned along with various seeds in small, 

 cylindrical, closed vessels containing a little damp 

 sand. Here the vessels were frequently rolled from 

 side to side or shaken, during the twenty-two hours 

 for which the experiment lasted, so as to excite the 

 ants and make them give off such odours as they 

 possessed, but no trace of injurious influence was 

 produced upon the seeds, which germinated and grew 

 normally afterwards. 



At Mr. Darwin's suggestion I made a long series 

 of experiments with formic acid, in which measured 

 quantities, pure or diluted, were placed in a watch- 

 glass on damp sand and surrounded by seeds, the 

 whole being enclosed in a covered tumbler, so that 

 the effects produced on the seeds by the vapour 



o 



