452 J. C. BRANNER — GEOLOGIC WORK OF ANTS 



species are much more active agents than others. We need concern our- 

 selves with only two large orders : the true ants belonging to the Hymen- 

 optera, and the termites, or so-called white ants, neuropteroid insects 

 which belong to the Isoptera, and are known all over Brazil by the popu- 

 lar Indian name of "cupim." And nothing is attempted in the way of a 

 study of the architecture of their nests and underground passages, save 

 in so far as such details will give a better idea of the geologic bearing of 

 these matters. 



The monumental work of Dr. Auguste Forel, "Les Fourmis de la 

 Suisse,'^ published at Zurich in 1874, will naturally be consulted by any 

 one especially interested in ants themselves and in their habits and 

 structures. 



It may be useful to suggest in this connection, however, that though 

 the ants of Switzerland and of temperate regions generally exhibit the 

 same ingenuity and intelligence as those of tropical countries, as geologic 

 agents they are very tame indeed in comparison with those of the tropics. 



In studjing the work of ants in the tropics one is constantly reminded 

 of Mr. Darwin^s studies of the work of earthworms. Mr. Darwin was 

 able to give the quantitative results of his studies. In the case of the 

 ants, unfortunately, quantitative results have not been possible. The 

 time occupied by them in doing a given amount of work varies so much 

 that quantitative observations, in order to have any value, would have to 

 be carried on upon many colonies and for a long period of time. The 

 results given at page 469 are an attempt at quantitative determination, 

 but it will be observed that it is not known how many individuals took 

 part in the work, while the time element involved in the calculation is 

 entirely lacking. It is hoped that observations may be undertaken by 

 geologists living in tropical countries with a view to settling these inter- 

 esting points. 



To illustrate this article especial pains have been taken to get as many 

 photographs and sketches as possible of the above-ground structures of 

 ants and termites, and the accompanying illustrations have been carefully 

 made by Mrs. Starks from photographs, most of them taken in Brazil by 

 myself or by my former assistant, Mr. Eoderic Crandall, now geologist of 

 the Geological Survey of Brazil (Servigo Geologico do Brazil). It seemed 

 better to have the drawings made rather than to use the original photo- 

 graphs, in spite of the evident suspicion of exaggeration or alteration, 

 whether intentional or accidental, to which all drawings are open. This 

 redrawing was the more necessary because the photographs were taken 

 hastily and under many unfavorable circumstances, and they are there- 

 fore often not good, or they are not available for reproduction as photo- 



