COMPOUND ORGANISMS 



201 



chemical reactions that have gone on and 

 are still going on within it. These reactions 

 are nicely adjusted, and are readily interfered 

 with or encouraged by the conditions under 

 which they take place. The result is per- 

 ceived in a delicate adjustment of growth 



Fig. 23A. Pdtigera canina, a lichen. P, the fructification. 



whereby the different parts are so correlated 

 to each other that excessive development 

 of one part carries with it its own order of 

 arrest, whilst deflection of nutrition to or 

 from any part will, of course, correspondingly 

 affect growth in that region. 



But, nevertheless, the parts of which the 



