SPECIAL PART: THE CHLOROPHYLL APPARATUS. 7 
was determined by inspection only, 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 under observation during the course of 
this study: Aster sfinosus Benth.; Baccharis emoryt Gray; Celtis pallida 
Torr.; Cereus giganteus Englm.; Condalia spathulaca Gray; Covillea tridentata 
Vail; Ephedra antisyphilitica C. A. Meyer; Fouquieria splendens Engim.; 
Franseria dumosa Gray; Keberlinia spinosa Zucc.; Krameria canescens Gray; 
Olneya tesota Gray; Parkinsonia aculeata L.; Parkinsonia microphylla Torr.; 
Parkinsonia torreyana Watson; Prosopis velutina Wooton; Salix nigra Marsh.; 
Sambucus mexicana Presl.; Zizyphus parryi Torr. 
SPECIAL PART: THE CHLOROPHYLL APPARATUS. 
ASTER SPINOSUS; BACCHARIS EMORYI. (Fig. 1.) 
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. 1.—Baccharts emoryt: A, segment from transverse section of young 
stem to show the character of cortical chlorophyll band (ch. 4.); B, sec- 
tion of leaf, magnified as in 4.* 
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. 
