THE LABIATE FAMILY. 217 



I will here call attention to a few additional facts. 

 First observe the number of " ribs " of the calyx, say, 

 of the very common species, 8. imnicula'ta. We may 

 represent this as follows : Being composed of five 

 sepals, and each sepal stands for a leaf, let d be their 

 mid-ribs, then where the margins are united there 

 would be none, as leaves have none there. But since 

 the weight of the bee is all on the lip in front, and the 

 slender tube of the corolla has to be supported, Nature 

 has run up, so to say, additional columns to strengthen 

 it ; and we shall find they are distributed as follows : — 



d 



m m 



d d 



m m 



d d 



m m 



where d stands for dorsal, i.e. the hack or mid-rib of the 

 sepals, while m stands for marginal. 



Now^, it will be noticed that the calyx is two -lipped. 

 The meaning of this is that there has been a tendency 

 to tear the calyx across. To prevent this the insertion 

 of marginal cords was made ; but in front, where the 

 strain is greatest, tioo cords {m m) have been added. 

 In another species (>S^. patens), with blue flowers, there 

 are hvo marginal cords at the sides, and a third is 

 inserted between the two in front. Moreover, the 

 cords are branched at their upper ends where the calyx 

 expands. 



