160 PROCEEDINGS OF THE ACADEMY OF [1879. 



half of the measured space. The galleries were in depth fully one- 

 eighth of an inch. This will give a rude notion of the extent to 

 which the underground space occupied by a single colony is exca- 

 vated. 



Another estimate was made of the quantit} 7 of earth thrown out 

 of a nest in the two days succeeding a heavy rain. The excava- 

 tions brought up from the seam of a brick that faced a grass plat, 

 and which were spread along a distance of eight inches, were 

 collected and measured. The result showed a solid contents of 

 six cubic inches. This was onty a part of the work of a formi- 

 cary in the time specified, during only a part of which the ants 

 were engaged in transporting pellets. 



The other factor in the calculation is the number of ants of 

 various species spread over any given surface of the earth. Ac- 

 curacy of count would be quite impossible; but if one will take 

 pains to observe the number of nests which may be seen in nearly 

 every open tract of country, he will be surprised at its vastness. 

 In some such rough observations, made in the open field, Mr. 

 McCook had concluded that it would be scarcelj' possible to dig 

 within an}' square foot of surface without uncovering the formi- 

 caiy of some, often of several, species of ants. There is of 

 course a difference in this respect between soils and sections; 

 but the fact is constant that innumerable myriads of ants are 

 everywhere located and operating as above described. As re- 

 sults of such labor, first, the ground is pulverized and brought in 

 great quantities to the surface, thus making good top soil for the 

 growth of vegetation. The nest by which these remarks were 

 illustrated shows that, insignificant in size as these insects are, 

 the labors of countless hosts through many years are by no means 

 insignificant in this shifting of the soil. Second, the aeration of 

 the soil, so needful for its productiveness, is thus largely pro- 

 moted. Third, the system of " pores," established by the gal- 

 leries which everywhere perforate the ground, affords, on the one 

 hand, free entrace for the rains into the earth, and, on the other 

 hand, a series of tubes through which, by capillar}' attraction, 

 the moisture may ascend to the roots of plants. In this geo- 

 graphical province (Philadelphia) perhaps the most numerous 

 species, and therefore the most effective toward the above results, 

 are T.csespitum and Lasius jlavus, both small species, the largest 

 workers being little more than one-eighth of an inch in length. 



The fate of the ants during the late heavy June rains had some- 

 what occupied Mr. McCook's attention. Where do the little 

 creatures find refuge? or do they find any sheltered spot within 

 their nest ? It would seem that the health and safety of the larvae 

 at least must require some protection from the water. But he 

 could not satisfy himself that Tetramorium has any such shelters. 

 The pellets of soil brought up after the rains were all damp, and 

 had evidently been reached b} r the water. The opened formicary 



