35 



liloll observed in Ampelopsis, etc, n that leaves partly covered 

 by othar leaves did not turn red. At times one can also 

 perceive in leaves infected by fungi, that certrdn parts 

 remain green for a noticeabliy long time. 



In connection with chromatophores, a fer; other brief 

 remarks on the red pigmen t of plants fanihocyanin) are 

 appropos. Its formation also is connected vath definite con- 

 ditions. In the study of these \7e meet again with the fac- 

 tors which are concerned in the formation of chlorophyll; 

 first of fell, light. The dependence of the anthocyanin for - 

 mation upon the action of light difiers from that of the 

 chlorophyll formation in that only in the case of certain 

 plants and organs is light indespensible for the develppiiient 

 of the red coloring matter. Many rhizomes, roots, bulbs, 

 and tubers ?/hich, under, normal conditions, remain continu- 

 ously vi/ithout light, are richly provided with anthocyanin. 

 On the otherhand, there are organs v^hich develop the red 

 coloring matter only upon exposure to light; for instance, 

 seedlings of Polygonum fagopyrum. v;hich B^talin*^ investi- 

 gated carefully. The fact has long been knov^n to breeders 

 9,nd to those interested in plants, that the formation of 

 pigment is suppressed in red leaved ornamental plants culti- 

 vated in the shade. According to Pynaert, the dependence uf- 

 on light is especially noticeable in Alternanthera atropur- 

 purpa and ColeuS.^ The blossoms of many plants also need 

 39 the action of light for the development of their red and 

 blue pigments; other plants, hov/ever, open normally- colored 

 blossoms in the dark, or blossoms that remain only a little 

 below the normal in the intensity of their coloring. In 

 Orchis ustulata , only the hood loses its color."* Fruits, 

 as well as blossoms , behave dissimalarly in the formation 

 of pigment under abnormal conditions of life. The fact that 

 apricots, apples, pears, etc. only redden on the side ex- 

 posed to the sun, has been cited often since Senebier. On 

 the other hand. Laurent^ has proved that vines with blue 



1. Einfl. d. Lichtes auf. d. herbstl. Verfarbund d. 

 Luabes. Sitzungsber. Niederrhein. Ges. Natur - u, Heilkunde 

 Bonn, 1891, p. 80. 



2. Die Einwirkung des Lichtes auf die Bildung d. roten 

 Pigm. Acta Horti Petrop. , 1879, T. VI. 



3. De I'infl. de la lumiere sur la veget, de pi. culti- 

 vees en serre. Bull. (Jongr. Intern, de Bot. §t d^Hortic.1884 , 

 p. 289. Therein also further examples (Dracaena, Pandanus 

 Veitchi, Saxifraga and others.) The leaves of the red beet de- 

 velop red coloring matter even in the dark (predominantly on 

 the veining. 



4. Compare the notes by Askenasy, Ueber den Einfluss 

 des Lichtes auf die Parbe der BlUte. Bot. Zeitung, 1876, Bd. 

 XXXIV, p. 1. also Benlaygue, Infl. de I'obscurite s. 1. devel, 

 d. fleurs. C, R. Acad. So. Paris 1901.T.CXZ1II , p. 720. 



5. Infl. de la radiation s^ la, coloration des raisins, 

 C. R. Soc. Hoy, Bot. Eq>:tgiq>ie. 1890 » T.-XXIX, 2. p. 71. 



