APPENDIX 



485 



The chief points of 

 growth are the tips of 

 the roots and branches 

 and the deUcate sappy 

 layer between the bark 

 and the wood (cambium, 

 Fig. 206). Injury to 

 any of these stops or 

 deranges growth at the 

 point injured. It is 

 chiefly through derange- 

 ment of some of these 

 functions, absorption, 



liquid or gaseous, conduction, photosynthesis, or growth, that 

 disease is caused. 



Fig. 205. — Stomata or breathing pores in the 

 epidermis. From Strasburger's textbook. 



Fig. 206. — Diagram of cross section of stem 

 showing circle of veins, m, pith ; i. f. c, 

 eambium ring. The portion of the vein 

 inside the ring is the wood and contains 

 large ducts. The portion outside of cam- 

 bium ring is the bark. From Strasburger's 

 textbook. 



