36 BOTANY. [chap. i. 



light. During the night the starch that has been formed 

 during the day^ in the cells of the leaves more especially, 

 is dissolved, and passes along the veins of the leaf into 

 the branches, and becomes diffused over every portion of 

 the plant, a certain portion being used up at once in the 

 formation of new cell-walls, the remainder being stored 

 away for future use in certain internal tissues, or very 

 frequently in underground parts, as bulbs, tubers, etc., 

 that become much swollen owing to the formation of 

 thin-walled tissue containing starch. Such swollen 

 underground parts usually serve as vegetative repro- 

 ductive bodies. 



Fig. 9. Cells of beet {Beta 

 maritima), containing agglome- 

 rations of crystals. (Highly mag- 

 nified.) 



(3) Crystals are of very common occurrence in the 

 cells of plants, and almost invariably consist of oxalate 

 of lime. When the crystals are very long and slender 

 they are often called rwphides, and occur in enormous 

 quantities in the cells of some plants. If the flower- 

 stalk of the common hyacinth is crushed, and a minute 

 quantity of the juice examined under the microscope, 

 numerous very slender, needle-shaped crystals will be 

 seen floating in the liquid. Crystals are present in 

 enormous quantities in the stems of old cactus plants, 

 rendering them quite brittle. 



The material forming crystals is not absorbed by the 

 plant as oxalate of lime from the soil, but is formed by 



