No. 449.] 



Sri/DIES ON THE PLANT CELL. 



Z11 



Botrydium), in the Rhodophycese {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 first visible 

 products of photosynthesis being other substances more of the 

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



a 



KiG. 2. — Plastids. «, Chloroplasts: i Vaucheria, wiih oil globules; 2 Bryopsis ; 3 

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

 starch, ^, Chromoplasts : i Tropaeolum, epidermal cell from calyx; 1 Fucus, 3 

 Callithamnion. c^ Chromatophores : r Spirogyra, with pyrenoids (/) and caryoids 

 (c); 2 Hydrodictyon, pyrenoid forming starch; 3 Nemalion ; 4 Anlhoceros, in divi- 

 sion and containing starch, d, Leucoplasts : i Phiijus, pkstid and starch grain at 

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

 deeper cells of root, with starch grains. AEier Meyer, Strasburger, P.lla, I imber- 

 Like 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 



