RESUME 495 



2. By opening the soil to atmospheric air and gases. 



3. By bringing to the surface large quantities of soil and sub- 



soil. 



4. By introducing into their subterranean excavations largq 



quantities of organic matter which must yield acids that 

 affect the soil and the subjacent rocks. 



5. By using these excavations for habitations and the produc- 



tion of gases that attack the soil and its contained minerals. 



Indirectly : 



6. By the periodic passage and circulation of meteoric waters 



through their extensive tunnels. 



7. By affecting the availability of the soil for agricultural pur- 



I 



8. By affecting the habitability of the land by man. 



9. By the destruction of crops. 



10. By the consumption (by termites) of dead plants and of tim- 

 bers and lumber used in houses and for the manufacture of 

 furniture, machinery, etcetera. 



Although the data available are defective, we seem to be warranted in 

 concluding that ants and termites are quite as important geologic agents 

 in tropical America as are the earthworms of temperate zones. 



They are also factors of great importance from an agricultural, eco- 

 nomic, and social point of view. 



Postscript 



Since this articie was in type I have received the following letter from 

 my Brazilian friend, Dr. Joaquim Lustosa, in regard to the subject of the 

 luminosity of termites mentioned on pages 491-492. The letter is dated 

 Lafayette, State of Minas Geraes, Brazil, July 8, 1910 : 



"I have just received authentic information to the effect that in the State of 

 Matto Grosso, in the low, swampy lands along streams, and especially in the 

 rainy months beginning with October, myriads of fireflies are seen covering 

 the ground. My informant, who has lately come from the upper part of Matto 



