356 EAMBLES OF A NATURALIST. 



manner. In all questions of this kind, practical 

 attempts which alone can decide the applicability of 

 the method, must necessarily follow upon all those 

 investigations of science which yield what may be 

 termed a theoretical solution of a problem. Con- 

 sidered from this point of view, it will be seen that 

 new problems rise for every special case. Thus, for 

 instance, in attacking an exclusively mining species, 

 an exact exploration of the scene of their operations 

 will be the first thing necessary, in order to discover 

 the starting point of the thousand galleries which 

 are constructed by the Termites. Next it would be 

 necessary to determine the spot at which the appa- 

 ratus should be applied, in order that the gas might 

 penetrate with the fewest obstacles into the very 

 heart of the settlement. Perhaps the insects when 

 thus attacked might defend themselves, like those of 

 Senegal, by walling up the passages which gave ad- 

 mittance to the deleterious gas, and in that case it 

 would be necessary to display a promptitude of 

 action which would be the only means of forestalling 

 the efforts of these little animals. Perhaps it would 

 be necessary to liberate the gas under a pressure 

 high enough to enable it to penetrate through the 

 whole extent of these edifices. Perhaps, indeed, 

 notwithstanding all these precautions the first at- 

 tempts might prove unsuccessful, even in the case of 

 isolated colonies like those of La Rochelle. Lastly, 

 it is very probable, or rather almost certain, that in 

 towns which have been generally infected like 

 Saintes or Rochefort, it would be necessary, after a 

 first success, to contend against new invasions, and 



