48 



Principles of Plant Culture. 



soil, some of which are used by the plant in growth. 

 As these useful matters are removed from the water of 

 the cells, to be formed into food (58), the supply is 

 replenished from the soil, not through any power of 

 selection possessed by the plant, but in accordance with 

 the law of diffusion. In like manner, the food formed 

 by the chlorophyll (58) finds its way to the. growing 

 parts. Soluble matters not used by the plant are not 

 taken in to the same extent as those that are needed, 

 because their distribution is less disturbed. 



The distribution of soluble matter in the plant is also 

 promoted by transpiration (74). 



SECTION IV. THE INNER STRUCTURE OF THE PLANTLET. 



Thus far, we have considered the plantlet mainly 

 from the outside. Before going farther, it is well to 

 learn also something of its 

 -Dinner structure. We have 

 Pal seen that all parts of the 

 plant are made up of cells 

 (12) and that these cells dif- 

 fer in form and office in the 

 different parts. The cells of 

 the leaf, for example, are 

 different in shape and in the 

 use they serve to the plant, 

 from those of the stem, 



FIG. 17. Showing section . . 



through leaf of Oldenburgh nOWCr or iruit 

 apple. Ep. epidermis; Pal 

 pali 

 s 



. . . 



alisade cells; I intercellular 64. The Epidermis (ep'-l- 

 paces. Highly magnified. See 



lso Figs. 13 and 20. der-mis) . The plant is cov- 



ered by thin, translucent skin that extends over the 



