THE LIVING CELL 43 
or red pigment called chromophyll. The chromoplastids may be 
circular, oval, needle-shaped, angular or fan-shaped and are 
averagely smaller than chloroplastids. They are responsible 
for the yellow and orange colors of many petals and sepals of 
flowers and of ripened fruits. The root of the carrot contains 
large numbers of them. 
(ec) Ceti Mempranes.—These are of three kinds, viz.: (1) 
The outer plasma membrane or ectoplasm, found as a transparent, 
colorless, outer bounding film of cvtoplasm enveloping the 
Fic. 23.—A, cell from the epidermis of the upper surface of the calyx of the 
Nasturtium (Zropeolum majus) with crystalline chromoplasts; B, cells from the 
petal of Lupinus luteus, with yellow chromoplasts; C, cell showing numerous chloro- 
plasts scattered through the cytoplasm. A, after Strasburger; B, after Frank. 
’ (Stevens.) 
granular, inner cytoplasm, the latter sometimes termed ‘“‘endo- 
plasm’? ; (2) the vacuolar membranes, clear bounding films of cyto- 
plasm surrounding sap vacuoles; and (3) the nuclear membrane, a 
clear, transparent film of protoplasm forming the outer bounding 
zone of the nucleus. All of these membranes are semipermeable 
membranes, since, in their living condition, they will permit the 
passage through them of water and certain crystalloidal (water- 
soluble) substances in solution while they will not admit the 
passage of other crystalloidal substances in solution. 
(f) CHONDRIOSOMES OF MrrocHonpRria.—These are small 
granular or rod-shaped protoplasmic bodies found scattered in 
