Larval Dimorphism 



ceedlngly compact. There are no chinks due 

 to bad building; no fissures due to the 

 weather; nothing but an apparently impene- 

 trable homogeneity. I see but one weak part 

 and that only in a few nests : it is the line 

 where the dome joins the surface of the stone. 

 An imperfect soldering between two materials 

 of different nature, cement and flint, may leave 

 a breach wide enough to admit besiegers as 

 thin as a hair. Nevertheless, the lens is far 

 from always finding an inlet of this kind on 

 the nests occupied by Anthrax-flies. 



And so I am ready to allow that the ani- 

 malcule wandering in search of its cell has the 

 whole area of the dome at its disposal when 

 selecting an entrance. Where the fine auger 

 of the Leucospis can enter, is there not room 

 enough for the even slimmer Anthrax-grub? 

 True, the Leucospis possesses muscular force 

 and a hard boring-tool. The Anthrax is ex- 

 tremely weak and has nothing but invincible 

 patience. It does at great length of time what 

 the other, furnished with superior implements, 

 accomplishes in three hours. This explains 

 the fortnight spent by the Anthrax under the 

 initial form, the object of which Is to over- 

 come the obstacle of the Mason's wall, to 



los 



