Details of Plate 13. 



Figs. 



A. Prosopis glandvlosa submerged in the Salton Sea 1906 to 1908. Only the wood cylinder was 



left in this specimen, the cortex and phloem having been entirely decorticated. 



B. Prosopis glandulosa after continuous submergence for two months in Lake Michigan water. 



Very little decortication had taken place at the completion of this period. 



C. Specimens shown in B after two months more of submergence in Lake Michigan water. Slight 



decortication is shown in the two middle transverse sections. 



D. Sections of Prosopis glandulosa after two months of submergence in Salton Sea water. The 



longitudinal sections show far more decortication than was indicated in B, the specimens 

 that had been submerged an equal time in Lake Michigan water. 



E. Four of the specimens shown in D have now advanced greatly in decortication during four 



months more of submergence in Salton Sea water. All of the phloem and cortex is raised 

 from the ends of the two long sections and entire decortication has occurred in the two 

 small transverse sections. Hydrolysis has advanced far in the cambial regions of the 

 sections which have been submerged constantly for six months in Salton Sea water. 



F. Prosopis glandulosa in transverse section. This shows the cortex (c), phloem (p), and xylem 



(x). In the phloem (p) the zones of alternating lignified (lig.) and unlignified (unlig.) 

 tissue are shown. Hydrolysis of the unlignified (unlig.) tissue here coincides with the 

 broken-down layers in D and E where the lignified (lig.) tissue is lifted in well-defined 

 layers, after the unlignified (unlig.) tissue was hydrolyzed. 



G. Prosopis pubescens photographed after two months of submergence in Lake Michigan water. 



Decortication is slight as in B. 



H. Same culture as G after two months of further submergence in Lake Michigan water. The 

 upper transverse section shows considerable decortication after four months of sub- 

 mergence in the Lake Michigan culture. 

 I. Prosopis pubescens after two months of submergence in Salton Sea water. Some decortication 



is shown in one transverse section. 

 J. Same culture as shown in I after two months more of submergence in Salton Sea water. 

 Marked decortication is indicated by the four transverse sections. 



K. Prosopis pubescens showing the cortex (c), phloem (p), and xylem (x) in an interesting relation 

 when compared with F. Here closely associated lignified (lig.) zones are separated by 

 very thin unlignified (unlig.) regions, consequently Prosopis pubescens does not decorti- 

 cate after the manner of Prosopis glandulosa. A comparison of K and F, and compari- 

 sons of B and C with G and H, also a comparison of D and E with I and J are instructive- 



