82 GLIMPSES OF NATURE. 



Given this power, then, we may see in the Biorhiza 

 an illustration of a youthful form which has acquired 

 an egg-laying habit. Its wingless state shows it to be 

 less perfect than its winged neighbours. But, as the 

 old strain strikes true, so out of the root-galls come 

 forth the typical and perfect insects, whose eggs in 

 turn stop short of their full development, as it were, 

 and give origin to the imperfect Biorhiza individuals. 



All the same, if we did not know this curious piece 

 of history, we might not have doubted that we were 

 dealing with two distinct species of gall-flies. The 

 lesson we learn is, that it is scarcely safe to assert, 

 and never safe to dogmatise, about the exact relation- 

 ships of living beings, because now and then they show 

 a tendency to become decidedly " mixed." 



