368 SMITH : APPLICATION OF THE THEORY OF 



When we consider that throughout the whole of these 

 periods transpiration is either very slow or altogether in abey- 

 ance since humidity is at or near saturation the whole time 

 and rain is almost continuous, it becomes at once pro- 

 bable that lack of mineral food is the important factor in 

 this cessation of growth. If no salts are obtained by the leaf 

 for a considerable period, the formation of new living tissues 

 must cease through want of the necessary mineral elements 

 which are normally brought into the leaf in sufficient quantities 

 by the transpiration current. If now these necessary minerals 

 were stored by the plant as reserve, the growth need not be 

 checked for want of them. We see therefore that in the case 

 of a plant with no reserve food a factor (the supply of mineral 

 food) may become limiting which would not be so in the case 

 of growth from reserve. The number of factors which must 

 all be simultaneously favourable to promote rapid growth in 

 plants which do not form stores of reserves is large. They 

 have been indicated above and include the various factors 

 upon which assimilation and transpiration depend as well as 

 those which promote the translocation- and elaboration of 

 food supplies. 



If now any one of these numerous factors may become the 

 limiting factor in the final product, growth, and may after 

 limiting growth for a shorter or longer period in its turn give 

 place to some other factor which becomes limiting, it will be 

 seen that the final growth curve may be very irregular. Not- 

 withstanding this irregularity the whole curve may be quite 

 in harmony with the theory of limiting factors, and if all the 

 factors weir know n every change of grout h might be aooounted 



for. Now it is just in cases of gTOWth without reserve stores 



that Beamingly inexplicable irregularities ocour. In my cases 



of growth from reserve some general regularity was a rule to 

 be detected, but I bave made observations of many cases of 



band to mouth' growth in which then-suits w ere so irregular 



that an explanation seemed bopeless. rlraus (IW) in his 

 measurements of Dendrocalamus giganteus at Buitenxorj 



