i)0 GLIMPSES IXrO PLANT-UFE 



brushed perfectly clean, and then bleached by 

 niixini;" a little chloride of lime in water and 

 lettini^" them soak in it till tliey are white and 

 free from odour. 



In a manufactory there must of necessity be a 

 series of windows on the different floors, not only 

 to let in lii;ht but for purposes of ventilation. 

 Now, the processes of tree-growth are carried on 

 without light in the stem, but air is necessary, and 

 it is supplied by means of small apertures called 

 lenticels. These are not open holes, but are more 

 like gratings which admit a small amount of air 

 through loosely-packed cells. 



These lenticels are the small brown specks 

 which ma)' be traced in great numbers on the 

 young branches of almost any tree. The}' remain 

 open through the spring and summer, admitting 

 the needful air to the interior of the bark, but 

 when the tree-growth is over for the season, and 

 air is no longer needed, a layer of cork forms 

 within the lenticel which entirely shuts it up and 

 keeps out the wintr)- cold. Thus it remains sealed 

 up till, by the growth of the cambium layer in the 

 following s[)ring, the corky barrier is split open 

 and air is a<rain admitted. 



