LEAVES io<> 



Each stomate leads into air spaces between the 

 cells, and is thus connected with the interior of the 

 leaf. 



The tissue and cells of a leaf (bifacial j' can be 

 understood by reference to the accompanying^ dia- 

 frram. Between the upper and under surfaces (jf 

 a leaf there is a la\cr, more i)r less thick, of soft 



LEAK SKCTIUN. 



green tissue known as iiiesophyll, and if we hold a 

 leaf to the sunlight we shall see the veins travers- 

 ing this tissue. 



The upper part of the mesoph}'ll consists ol 

 elongated cells arranged at right angles to the 



' Thai is, a leaf like the l)cech ur sycamore, havinjj an upper and 

 under surface ; vertical leaves, like the iris, have palisade tissue on 

 both sides. 



