102 ANIMAL INTELLIGENCE. 



until by chance I laid them bare. In one case I knew that the 

 destruction of the wall had only taken place ten days before, so 

 that the seeds had sprouted in the interval. 



My experiments also tend to confirm this, and to favour the 

 belief that the non-germination of the seeds is due to some 

 direct influence voluntarily exercised by the ants, and not 

 merely to the conditions found in the nest, or to acid vapours 

 which in certain cases are given off by the ants themselves. 



These experiments consisted in confining a large 

 number of harvesting ants with their queen and larvae in 

 a glass test-tube partly filled with damp soil and various 

 seeds, the whole being closed with a cork in the mouth 

 of the test-tube. Under these circumstances the seeds 

 all sprouted, showing that mere confinement in an atmo- 

 sphere of exhalations from the ants did not prevent germi- 

 nation. Another series of experiments, undertaken at the 

 suggestion of Mr. Darwin, on the effects of an atmosphere 

 of formic acid, showed that although this vapour was very 

 injurious to the seeds, it did not prevent their incipient 

 germination. Therefore it yet remains to be ascertained 

 why the seeds do not germinate in the granaries of the 

 ants. 



But in whatever way the ants manage to prevent ger- 

 mination, it is certain that they are aware of the 

 importance in this connection of keeping the seeds as 

 dry as possible ; for Moggridge repeatedly observed that 

 when the seeds which had been stored proved over-moist, 

 the ants again took them out and spread them in the sun 

 to dry, to be again brought into the nest after a sufficient 

 exposure. 



Lastly, he also repeatedly observed the most surprising 

 and interesting fact that when, as we have seen was occa- 

 sionally the case, the seeds did begin to germinate in the 

 nests, the ants knew the most effective method of pre- 

 venting the germination from proceeding ; for he found 

 that in these cases the ants gnawed off the tips of the 

 radicles. This fact deserves to be considered as one of 

 the most remarkable among the many remarkable facts of 

 ant-p sy chology . 



Passing on now to the harvest'' g or agricultural ants 



