BUDS AND LEAVES. 29 



iii. The substance that consfcitutes the lamina (a word 

 tliat means plates or scales, hence the term as applied to 

 the blade of a leaf, that is, the tliin expanded portion of 

 the green leaf, the petiole of the flower, or the sepal of the 

 calyx) is called cellular tissue, and the thin green skin 

 which covers the whole is the cuticle. 



65. If you take any thick fleshy leaf, as the Madeira-vine 

 (BasellacecB baselloides), pond-lily, or cabbage, you can with 

 a delicate penknife or a needle-point lift this covering or 

 cuticle, and discover beneath the very different texture of 

 the cellular tissue. Cellular tissue, when magnified by a 

 strong glass, presents the appearance of an immense num- 

 ber of little sacks or cells cohering together, and are in re- 

 ality tiny bladders or sacks in a greater or less degree of 

 cohesion. 



66. The cuticle, under the microscope, exhibits hundreds 

 of minute pores, especially that from the outside of the 

 leaf. These mouths oi breathing-places are called stoinata. 



67. In my remarks upon the epidermis, I told you some- 

 thing about the breathing-pores. Those in the cuticle are 

 the same in their appearance and office. Leaves are fur- 

 nished with these mouths to inhale such things as are 

 necessary for the plant, and exhale all superfluous or un- 

 necessary gases, moisture, etc., elaborated by the process 



bution of the veins in the leaf always correspond. When the branches are whorled the leaves 

 are also whorled. as in the rhododendron, or the veins of the individual leaf, as in the common 

 sycnraore and lady's-mantie. When the leaf has a petiole, the tree has its trunk unbranched 

 near the base, as is the case in the sycamore, Cottonwood, etc. ; and when the leaf has no petiole, 

 the trunk is branched from the root, as in the common ornamental low shrubs, laurel, holly, 

 lagaerstremia, bo.x, etc. I mention Prof. McC.'s theory that you may in yonr own observations 

 verify the endless variety that is brought out by the Great Creator from one type. Everything 

 in the whole round of scientific facts goes to prove that the idea of creation was conceived upon 

 one broad, comprehensive, unified thought; each detail being worked out from the great central 

 original type. 



64. What is the lamina? What doe? the word lamina mean? To what ap- 

 plied ? What is the substance called that constitutes the lamina of the leaf? 

 What is the thin green covering called ? 



65. When this is removed, what is found beneath ? Of what does this cellular 

 tissue consist? 



66. How does the cuticle appear under a strong glass ? 



67. The offices of these pores ? 



