116 INDIAN FOREST MEMOIRS. 



hi which the plant is naturally found and that therefore the results obtained will to a 

 considerable extent apply to areas other than that in which the information has been collect- 

 ed. Alterations in climate, by affecting the period of vegetative activity, will no doubt to 

 some extent modify the above arrangement as regards fire-damage. 



In the present paper, however, what appears to be the normal life history of the culms 

 of each species has been carefully explained and the connection between this development 

 and the damage done to the plant by fire has been indicated. This information therefore 

 will, it is believed, enable anyone to form a good idea of the liability of these species to fire 

 damage in any particular locality, by observing the differences in the life history produced 

 by local climatic conditions. 



As regards ability to thrive in a dry soil, the arrangement given above merely refers 

 to what is believed to be the average capacity of the species, as it occurs in nature. Thus 

 the swamp form of Saccharum spontaneum can only thrive, i.e. attain average dimensions 

 on a soil containing large quantities of water and the quantity of water actually utilised by 

 a plant of average vigour of this form is probably not less than that utilised by an average 

 plant of Saccharum Munja. On the other hand, however, the majority of the individuals 

 composing the species Saccharum spontaneum, as it exists in nature, do not belong to the 

 typical swamp form but to the forms commonly found on dry sand and wet agricultural 

 lands. Taking these into consideration therefore the average plant of Saccharum spon- 

 taneum is able to thrive on a drier soil than the average individual of Saccharum Munja. 



A similar point of view has been taken in arranging the species with regard to other 

 factors. 



Thus as regards soil-aeration in species like A ndropogon m,onticola, Saccharum Munja, 

 and A ristida, which in nature as a rule are found on well-aerated soil, a comparatively few 

 individuals can be found growing well on heavy, less aerated soil. Plants of all these 

 species taken from well-aerated soil and then cultivated in Dehra Dun on loam have all 

 shown in a single season : — 



(1) Some plants which entirely fail to adapt themselves to the new soil and die, or 



which adapt themselves with difficulty and show inferior growth. 



(2) Some plants which adapt themselves at once to the new soil and show average 



dimensions. 



We almost certainly have an example here of individual variation and ot the power 

 possessed by individual plants, in a greater or less degree, of adapting themselves to new 

 conditions, and if the comparatively few individuals of these species which can be found in 

 nature growing on heavy soil are experimentally cultivated, they would almost certainly 

 show greater capacity for enduring poor soil aeration (probably equal to that of Saccharum 

 Narenga or Erianthus) than those taken from sandy, stony places. 



At the same time the average plant of these species, at all events in the present locality, 

 certainly does not occur in dense, poorly aerated soil and the above arrangement has been 



' [ 116 } 



