40 



EXPEEIMEKTS IN BLUEBERRY CULTURE. 



grow as luxuriantly as when the plants are in a peat soil. From 

 experiments with the growing of blueberries in sand watered with 

 peat water it is known that such water furnishes the food materials 

 necessary for vigorous growth. It is reasonable to conclude, there- 

 fore, that the chief nourishment of a blueberry plant growing on a 

 pure sjihagnum himnnock comes from the bog water sucked up by 

 the sphagnum and not from the sphagnum itself. 



PECULIARITIES OF NUTRITION. 



(13) The swamp blueberry is devoid of root hairs, the minute organs 

 through which the ordinary plants of agriculture absorb their 



moisture AND FOOD. 



The structure of the rootlets of ordinary agricultural plants may 

 be understood by reference to figures 11 to 13, which illustrate these 

 organs as they occur in a wheat seedling germinated between layers 

 of moist blotting paper. Attention is directed particularly to the 



Pig. 11. — Root of a wheat plant, showing the root hairs. (Natiu-al size.) 

 Fig. 12. — Portion of a wheat root, with root hairs. (Enlarged 10 diameters.). 

 Fig. 13. — Tip of the root hair of a wheat plant. (Enlarged 1,000 diameters.) 



root hairs. It will be observed that the wall of the root hair is very 

 thin, appearing in optical section as a mere line with barely measur- 

 able thickness, even when highly magnified. Furthermore, the sur- 

 face area of the root hairs is many times greater than that of the root 

 itself. The chief function of these root hairs is to absorb for the 

 use of the plant the soil moisture and the plant-food materials dis- 

 solved in it, a function which the root hairs are enabled to perform 

 with great efficiency because of the two characteristics just men- 

 tioned — their large surface area and the thinness of their walls. 



The rootlets of the blueberry are remarkable in having no root 

 hairs whatever, as may be seen by reference to figures 14 to IG. The 

 w^alls of the superficial, or epidermal, cells of the rootlets are thick, 

 measuring 0.00005 to 0.0001 of an inch (1.3 to 2.5 fi), while the walls 

 of the root hairs of Avheat are one-fourth to one-sixth as thick, 

 so thin, in fact, that they could be measured only with difficulty 



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