SUPPOSED POWEES OF COUNTING. 283 



eacli species. How, then, does the insect know when her 

 task is fulfilled ? Not by the cell being filled, for if 

 some be removed she does not replace them. When 

 she has brought her complement she considers her task 

 accomplished, whether the victims are still there or 

 not. How, then, does she know when she has made 

 up the number twenty-four ? Perhaps it will be said 

 that each species feels some mysterious and innate 

 tendency to provide a certain number of victims. 

 This would not under any circumstances be an ex- 

 planation, nor is it in accordance with the facts. In 

 the genus Eumenes the males are much smaller 

 than the females. Now, in the hive bees, humble 

 bees, wasps, and other insects Avhere such a differ- 

 ence occurs, but where the young are directly fed, it 

 is, of course, obvious that the quantity can be pro- 

 portioned to the appetite of the grub. But in insects 

 with the habits of Eumenes and Ammophila the case is 

 different, because the food is stored up once for all. 

 Now, it is evident that if a female grub was supplied 

 with only food enough for a male, she would starve to 

 death ; while if a male grub were given enough for a 

 female it would have too much. No such waste, how- 

 ever, occurs. In some mysterious manner the mother 

 knows whether the egg will produce a male or female 

 grub, and apportions the quantity of food accordingly. 

 She does not change the species or size of her prey ; 

 but if the egg is male she supplies five, if female ten, 

 victims. Does she count ? Certainly this seems very 

 like a commencement of arithmetic. At the same time, 

 it would be very desirable to have additional evidence 

 before we can arrive at any certaia conclusion. 



Considering how much has been written on instinct, 



