So GLIMPSES OF NATURE. 



galls from which they spring : so that, at first sight, 

 an element of mystery clearly attaches to these wing- 

 less females. 



From another part of the tree, in spring, issue forth 

 the ordinary gall-flies. They arise from the galls 

 borne on the ends of the branches, and these latter 

 insects are winged, and exhibit a due proportion of 

 both sexes. To the wingless mothers of the roots 

 the name of Biorhizas has been given ; while the 

 winged males and females are placed in the group 

 known by the term Teras. That the two kinds of 

 insects are of different species would appear to be 

 a very plain and reasonable inference. Habit and 

 appearance are surely much more clearly defined and 

 separated here than in the case of our crows. This 

 much goes without saying. But all has not yet been 

 told about the two kinds of gall-flies. 



From the roots, then, come the Biorhizas. They 

 climb up the tree in a slow and deliberate fashion, as 

 becomes insects which have no means of flight. Then 

 they pass to the branches of the tree, and climb out 

 to the very ends thereof. Next they begin to lay eggs 

 (which, by the way, are not fertilised, of course) in 

 the branches, and each egg is developed inside a gall. 

 Out of these Biorhiza-eggs, strange to relate, come the 

 winged Teras insects, so that first of all we see appa- 

 rently one species of animal giving origin to another 

 and entirely distinct species. The story then proceeds 

 to show that the Teras insects in their turn (winged 

 males and females as they are) produce fertilised eggs, 

 which the mother Teras deposits in the roots of the 

 tree. 



From these root-galls, as we have seen, the wing- 

 less Biorhizas are duly developed ; so that we find in 



