No. 449.] 



STUDIES ON THE PLANT CELL. 



377 



Botrydium), in the Rhodophyceae (e. g. Polysiphonia) and also 

 in the palisade cells of leaves. Chloroplasts after exposure to 

 light generally contain starch but in some plants this substance 

 is never formed (e. g. Vaucheria, Fig. 2 A i), the nrsFvrsible 

 products of photosynthesis being other substances more of the 

 nature of oil. It is not known whether the starch grain in the 



PIG. 2. Plastids. a, Chloroplasts: i Vaucheria, with oil globules; 2 Bryopsis ; 3 

 moss (Funaria), in division and containing starch grains ; 4 Oxalis, with a grain of 

 starch, b, Chromoplasts : i Tropaeolum, epidermal cell from calyx; 2 Fucus, 3 

 Callithamnion. c, Chromatophores : i Spirogyra, with pyrenoids (/) and caryoicls 

 (c); 2 Hydrodictyon, pyreuoid forming starch; 3 Nemalion; 4 Anthoceros, in divi- 

 sion and containing starch, d, Leucoplasts : i Ph.ijus, pUstid and starch grain at 

 the side of the nucleus ; 2 Iris, from root and containing oil globules ; 3 Iris, in 

 deeper cells of root, with starch grains. After Meyer, Strasburger, P.lla, 1 imber- 

 l.ike and Schimper. 



chloroplast results from the direct change of some of the pro- 

 teid substance or whether it is a secretion. The conditions 

 are somewhat different when pyrenoids are present in a chro- 

 matophore as will be described presently. 



The Chloroplasts of higher plants may change color under 

 various conditions and become chromoplasts. Some of the best 



