SPECIAL part: the CHLOROPHYLL APPARATUS. 



was determined by inspection onl3% and all chloroplastids that from com- 

 parison were seen to be normally colored were classed as being- functional 

 and were considered as having- adequate amounts of light and of air. 



The following- plants were passed imder observation during the course of 

 this study: Aster spinosns Benth.; Baccharis emoryi Gray; Celtis pallida 

 Torr.; Cernis gigantcus Englm.; Condalia spatJmlaca Gray; Covillea tridentata 

 Vail; Ephedra antisyphilitica C. A. Meyer; Foiiqideria splendens Englm.; 

 Franseria djdnosa Gray; Ka^berlinia spinosa Zucc; Kramer ia caiiescens Gray; 

 Olneya tesota Gray; ParJcinsoiiia aadeata L.; Parkinsoniainicrophylla Torr.; 

 Parkinsonia torreyana Watson; Prosopis velutina Wooton; Salix nigra Marsh. ; 

 SaDibucits mcxicana Presl.; Zizyp/nis parry i Tow. 



SPECIAL PART: THE CHLOROPHYLL APPARATUS. 



Aster spinosus; Baccharis emoryi. (Fig. i.) 

 These plants inhabit the wash along- the river and the irrigating- and 

 wayside ditches, where water is frequently to be found. Aster spinosus is 

 an annual with perennial root; Baccharis emoryi is perennial. Both Aster 

 and Baccharis are usually devoid of leaves, but the young- portions at least 

 are supplied with rudimentary ones. 



Fig. I. — Baccharis emoryi: A., segment from transverse section of young 

 stem to show the character of cortical chlorophyll band {ch. b.) ; i>', sec- 

 tion of leaf, magnified as in A."^ 



Chlorophyll of the stem is confined to the cortex in both species and in 

 both the chlorenchyma is palisade. The palisade in the stems of each also 

 closely resembles that in the rudimentary leaves of the same species. This 

 similarity in the structure of the chlorophyll band* in the stem and of the 



*In all figures chlorophyll is indicated by stippling. 



