THE PROTOPLAST AS HOUSE-BUILDER 



31 



Great honour is put upon the 

 cell after death, however ; it is 

 dignified with a new name a 

 name of sixteen letters as 

 inelegant as it is long. The 

 lifeless structure becomes, in 

 fact, a sclerenchymatous cell 

 the name implying that the 

 cell has had something hard 

 put into it ; for the term is 

 derived from two Greek words 

 skleros, hard, and enchuma, 

 anything poured or put in. 



Sclerenchymatous cells 

 occur in the gritty centre of 

 the pear, in the stones of the 

 peach, cherry, etc., and in the 

 shell of the common hazel-nut. 

 Lignin takes a deeper yellow 

 than cellulose when treated 

 with iodine, and it becomes 

 brown when treated with iodine 

 and sulphuric acid. 



Suberin, or cork substance 

 (Lat. suber, cork), is another of 

 the secondary deposits of cells. 

 Like cellulose and lignin, it is 

 coloured yellow by iodine, but 

 it resists the action of sul- 

 phuric acid. Cork cells are 

 tough without being woody. 

 Parts of plants the fluids of 

 which require to be protected 

 from evaporation, are usually 

 surrounded by cork cells, as 

 the stems and older branches 

 of trees, in which the sap cir- 

 culates. In young and 

 quickly growing trees the 

 epidermis (outer skin) of the 

 stem, being unable to stretch 

 fast enough, often gets torn, 

 and then the busy protoplasts 

 cover the wound with a special 



Photo by] 



Ste P' 



FIG. 51. FLOWERING RUSH (Butomus umbellatus). 



A handsome waterside plant, three or four feet in height, with an 



umbel of crimson flowers. EUROPE, ASIA. 



