EXUDATIONS AND ROTTING. 229 



Rankness is, in fact, in many respects analogous 

 to etiolation in so far as the tissues are soft and 

 surcharged with water, but it differs fundamentally 

 in the deep green of the chlorophyll : this may lead 

 to abundant assimilation if free access of air and 

 drier conditions can be gradually brought about. 

 Any sudden drying, however, may be fatal to the 

 tender tissues. 



Rankness commonly depends on excess of food 

 materials, especially nitrogenous manures, as may 

 be seen in meadows and cornfields where the 

 manure heaps have remained on the ground and 

 saturated it to excess as compared with the rest 

 of the soil ; this may often be observed with 

 weeds, etc., in the neighbourhood of farm- 

 buildings. If the period of rank growth is 

 accompanied and followed by days of suitably 

 bright sunshine and dry air, the increase of vege- 

 tative structures usually results in increased 

 flowering, heavy crops, or strong wood ; but if the 

 rankness continues too long, or is accompanied 

 by wet and dull weather, the watery tissues 

 are peculiarly susceptible to attacks of fungi 

 and insects, and to damage by sudden frosts 

 or chilly winds. Rankness affords, in fact, a 

 typical illustration of predisposition to disease. 

 Damping off. When seedlings are too closely 

 crowded in beds kept too damp, or in moist 

 weather, they are very apt to rot away, with all 

 the symptoms spreading from a centre, con- 

 tagious infection, mycelia on and in the tissues, 

 etc. of a fungus attack. The commonest agent 



