18 Abnormal Outgroivths or Intumescences in Hibiscus vitifolius. 



Effects of Light, 



Number 

 of experi- 

 ment. 



10a 



105 



11 



12a 



12b 



13 



14 



15« 



155 



Conditions of 

 experiment. 



Poor light ; no sun 



Light passing through 

 yellow glass 

 | Light passing through a 

 ; solution of potassium 

 j chromate 



' Light passing through red 

 glass 



I Light passing through 



blue glass 

 i Light passing through a 

 solution of copper sul- 

 phate and ammonia 

 Light passing through 



gre3n glass 

 Light passing through 



whitewashed glass 

 Plant in darkness in a 



greenhouse 

 Plant in darkness under a 

 zinc cylinder in the open 



Result, 



No outgrowths 



formed 

 Outgrowths 



formed 



No outgrowths 

 formed 



Outgrowths 



formed 

 No outgrowths 

 formed 



Remarks. 



Effects of Temperature. 



The formation of outgrowths (pr-ovided there is adequate moisture and light) is 

 -promoted by a high temperature. 



The conclusions drawn from the above experiments are, that the 

 outgrowths are formed in a moist atmosphere, provided that there is 

 also adequate light and heat. 



The immediate effect of the damp atmosphere is to check transpira- 

 tion. This, in its turn, by blocking the tissues with water, disturbs 

 the normal course of metabolism, and so leads (when the light and 

 lieat are sufficient) to changes in the metabolic activity of the plant, as 

 is shown by the following facts : — 



1. The outgrowths only develop if transpiration is reduced. 



2. The outgrowths are chiefly formed on organs which are actively 



assimilating, e.g., under ordinary, red or yellow glass ; but only 

 if transpiratory activity is lowered : they are not formed in 

 the open. 



3. They only occur {ceteris 'paribus) in plants in which there is an 



accumulation of starch. 



4. They are formed under clear glass and under red and yellow 



glass, but not under blue or green glass, and in no case in 

 darkness. 



