SAP. 59 



But growth under such circumstances will 

 not be long maintained, unless the roots are 

 secured from the reach of frost : for, if frozen 

 they cannot act, and will, consequently, be un- 

 able to replace the sap of which the stem is 

 emptied by the attraction of the buds converted 

 into branches, and by the perspiration of the 

 leaves. 



Whatever tends to condense the sap, such 

 as a dry and heated atmosphere, or an inter- 

 ruption of its rapid flow, or a great decomposi- 

 tion of carbonic acid by full exposure to light, 

 has the property of causing excessive vigor 

 to be diminished, and flower-buds to be pro- 

 duced. 



While, on the other hand, whatever tends to 

 dilute the sap, such as the free and rapid circu- 

 lation of it, a damp atmosphere, or a great ac- 

 cumulation of oxygen in consequence of the 

 imperfect decomposition of carbonic acid, has 

 the property of causing excessively rapid 

 growth, and an exclusive production of leaf- 

 buds. 



Condensed or accumulated sap is, therefore, 

 a great cause of fertility. 



And thin fluid, not being elaborated, is a 

 great cause of sterility. 



