GUMMING OF THE PEACH. 491 



2. Gumming — Apostaxis. Plants contain in their 

 economy a substance called gum. This is trans- 

 formed as occasion requires. Its composition is, of 

 carbon twelve parts, of hydrogen and oxygen eleven 

 each ; while that of starch is one part less of the 

 latter two, which are the elements of water, so that 

 the elimination of these two parts transforms it into 

 starch. Sometimes the tree stores up gum for 

 future use. The cells become full, and often, by 

 their lesion, cause the spaces between them to be 

 filled. If one cell is broken, the gum will flow 

 until there is no more room for it, the cell being 

 constantly replenished. So far, its effects may not 

 be injurious ; but if any break takes place in the 

 outer bark, the gum exudes ; and, as the air and 

 moisture are admitted, the decay of a part, or even 

 the whole of the tree, may be the result, either from 

 simple decomposition or from corrosion. 



3. Profusion of Sap. Page 462. 



4. Vitiation of the Sap) — Veneficium. Page 476. 



5. Decay — Caries. Page 468. 



6. Sun-stroke — Desiccatis. Page 473. 



7. Wounds — Vulnera. Page 474. 



