INTELLIGENCE OF ANTS. 817 



not particular as to the material which they collect and store up for 

 soil, provided that it is a material on which the fungus will grow 

 orange-peel, certain flowers, etc., being equally acceptable to them. 

 But they are very particular regarding the ventilation of their un- 

 derground storehouses, on a suitable degree of which the successful 

 growth of the fungus presumably depends. They therefore have 

 numerous holes or ventilating shafts which lead up to the surface 

 from the storehouses or underground gardens, and these they either 

 open or close according to the horticultural requirements as regards 

 temperature and moisture. If the leaves are either too damp or too 

 dry, they will not grow the fungus, and therefore in gathering the 

 leaves the ants are very particular that they should neither be the one 

 nor the other. Thus Bates observed : 



If a sudden shower should come on, the ants do not carry the wet pieces into 

 the burrows, but throw them down near the entrances ; should the weather 

 clear up again, these pieces are picked up when nearly dried and taken inside ; 

 should the rain, however, continue, they get sodden down into the ground, and 

 are left there. On the contrary, in dry and hot weather, wlien the leaves would 

 get dried up before they could be conveyed to the nest, the ants, when in ex- 

 posed situations, do not go out at all during the hot hours, but bring in their 

 leafy burdens in the cool of the day and during the night. 



Dr. Ellendorf made the experiment of interrupting the advance of 

 a column of these ants, with the interesting result which he thus de- 

 scribes in a letter to Btichner : 



Thick dry grass stood on either side of their narrow road, so that they could 

 not pass through it with the load on their heads. I placed a dry branch, nearly 

 a foot in diameter, obliquely across their path, and pressed it down so tightly on 

 the ground that they could not pass underneath. The first comers crawled be- 

 neath the branch as far as they could, and then tried to climb over, but failed 

 owing to the weight on their heads. Meanwhile the unloaded ants from the 

 other side came on, and when these succeeded in climbing over the bough there 

 was such a crush that the unladen ants had to clamber over the laden, and the 

 result was a terrible muddle. I now w^alked along the train, and found that all 

 the ants with their bannerets on their heads were standing still, thickly pressed 

 together, awaiting the word of command from the front. "When I turned back 

 to the obstacle, I was astonished to see that the loads had been laid aside by 

 more than a foot's length of the column, one imitating the other. And now 

 work began on both sides of the branch, and in about half an hour a tunnel was 

 maele beneath it. Each ant then took up its burden again, and the march was 

 resumed in the most perfect order. 



The operations here described show clearly that these ants act upon 

 the principle of the division of labor. In this connection I may also 

 quote an observation of Belt, which shows this fact in perhaps even a 

 stronger light. He says : 



Between the old burrows and the new one was a steep slope. Instead of 

 descending this with their burdens, they cast them down on the top of the slope, 

 VOL. XIX. 52 



