177 



it "was operated upon, which, having returned have commenced their 

 nest anew ? 



In using chemical fumes also, there may be some chamber Avhich 

 has not been reached, and in which ants are alive. This will, if left, 

 certainly carry on the nest, and it is certain that chemical fumes 

 cannot kill those which were away from home at the time they were 

 applied. Some nests also are held by separate families and 

 although they form one community, still their burrows or runs are 

 separate and distinct, and if one such run, burrow, pocket, or nest is 

 left untouched, the nest must of course be considered as incompletely 

 destroyed. 



The course pointed out therefore, is for plantei's to continue a 

 persistent and daily attack until they are certain the insects are 

 exterminated, whatever the means used, and not to think that any 

 method or system will, IN A MAGICAL WAY, ONCE AND FOR 

 ALL, DESTROY BY A SINGLE APPLICATION. Certain it 

 is, no system can or ever will do this until we can devise 

 means to attract every wanderer home previous to setting about 

 the operation of destroying the nest. Water will drown, Tar 

 will stifle. Sulphur will asphyxiate. Cyanide of Potassium will 

 poison, and Fire will consume, but unless carefully and continuously 

 applied, the operator will fail to effectually eradicate the Parasol Ant; 

 but if he pursues the policy of waging ceaseless Avar, and treating a 

 parasol ant's nest as he Avould a house on fire, (i.e.) attempt to subdue 

 it as soon as seen and continue until he has extinguished it, and if 

 (happy day for Trinidad) all the planters were a join in a united 

 attempt at the same season, this pest would not do the damage 

 it now does to Agriculture, but Avould soon be reduced in numbers, 

 and practically harmless to our Agri-Horticultural Industries. 



No. 32 — Origin of Sex. 



The qiiestion of the origin of sex, has long been a difficult one, 

 but our knoAvledge is being gradually extended. 



In H. J. Webber's article in "American Naturalist" (February, 

 1892), he recapitulates the results of some of Young's experiments, 

 in which among tadpoles the percentage of females was 57 in a 

 hundred. Fed on beef the percentage of females was raised to 78 

 per cent. Fed on fish to 81, and fed on the flesh of frogs the percent- 

 age of females became 92, or 92 females to 8 males out of every hun- 

 dred. And these changes are possible, owing to the tadpole " passing 



