Cll. IX. I LEAVES. 47 



great Being, who watches with unceasing care over his vast 

 creation. To observe the progress of life, whether in the ve- 

 getable or animal kingdom, is highly interesting to an inves- 

 tigating mind ; but here the power of man can achieve 

 nothing ; he may plant and water, but God alone giveth the 

 increase. 



177. A bud lives; an infant lives; both are destined to 

 grow and to pass through physical changes ; but the bud, 

 although active with a principle of life, knows not its own 

 existence ; while the infant becomes conscious of its own pow- 

 ers and faculties, capable of loving those who have con- 

 tributed to its well-being, and of adoring the great Author of 

 its existence. 



CHAPTER IX. 



Of Leaves. 



78. The leaf is generally a thin, flat organ, consisting of 

 an expansion of the fibres of the bark, connected by a substance 

 which is called the cellular tissue ; the whole is covered with 

 a green coat or skin called the cuticle. 



179. Leaves are furnished with pores for exhaling and in- 

 haling gases ; and as they present to the air a more extended 

 surface than all other parts of the plant, they are of great utili- 

 ty to the vegetable, by imbibing suitable nourishment, and 

 throwing off such gases as would be useless or injurious. 



ISO. We have seen how the bud is formed, and by what cu- 

 rious means the principle of vegetable life which it contains is 

 preserved and protected through the cold and dampness of win- 

 ter. In the spring, when the sun has turned his course towards 

 the north, re-crossed the equator, and is advancing towards the 

 tropic of Cancer,* the vegetable world in our region quickened 

 by its stimulating warmth, begins to awaken from its dormant 

 state ; the leaf-buds expand, and soon bursting their envelopes, 

 the green leaves come forth. 



* It is here presumed that the pupil has been instructed in the appa- 

 course of the sun, as explained in the common school geographies. 



177. What comparison may be made between a bud and an infant 1 ? 



ITS What is the leaf"? 



179 How do leakes inhale and exhale gases ? 



180 When do the leaves usually appear 1 



