34 



Above all others, the seedlings of many gymnosperms 

 and alg^ various algae are to be counted as exceptions to 

 the rule, so far as the need of light is concerned. They 

 become green even iii the dark, if the food materials of the 

 endosperm are at their disposal , ie. if organic food is 

 furnished them from without*"^ Well worth noticing is the 

 fact, that the formation of chlorophyll can be suD-oressed, 

 at least for lower organisms, bu^ an ov er- abundant ^su^oply' 

 of organic food. Zumstein «, obtained in this way colorless 

 Euglena ( E. rrracilis ) in which the green color was restored 

 by the use of organic substances, Zarsten^ found analogies 

 in diatoms, 



^9 ^11 organs, not turning green normally, but for some 

 reason, remaining colorless or yellow, contain chromato- 

 phores vihloh are yellowish pigmented or completely color- 

 less. Their nuniber per cell often remains below the normal, 

 their size usually is sub-normal also; often chromatophores 

 being demonstrable only in the form of tiny grains.. In many 

 king_s of variegated leaves, they appear to be entirely lack- 

 ing in the white parts, as, for instance, accordiiig to Winl:- 

 ler4 in Pandamus Veitchi, 



Finally those arrested developments should be consid- 

 ered, in which normal chlorophyll, grains are indeed, devel- 

 oped but are "hindered" from transforming into yellow or red 

 chromatophores, A good example of this is given by the 

 green flecked lemons, where the ripening processes have been 

 •Checked on the spots infested by Aspidiotus narii. ° Even 

 autumnal coloration can be prevented in places by external 



1. Literature citations Artari, Zut Srnahrungsphys . d, 

 grunen Algen, Bericht d. D. Bot. Ges., 1901, Bd. }CIX, p. 7, 

 Compare also Matruchot and Molliard, Variations de structure 

 sous I'infl. du milieu nutritif. Rev, Gen. Bot. 1902, T. XIV, 113. 



2, Z. Morph. u, Phys, der Buglena Gracilis, Pringsheim's 

 Jahrb, f, wiss, Bot., 1900, Bd. XXZIV, p. 149, Compare Bei- 



jerinck, Kulturversuche mit Zoochlorellen etc. Bot, Ztg.1890, 

 Bd, XIVIII, p. 7E4 (Beobacht. an Scendesmus) ; Kruger, Ueb. 

 einige aus Saftfllissen reingezuchete Algen, Zopfs Beitr., 

 1894, Bd, IV, Kurze Ch^rakteristik einiger ne-id. Organismen 

 im Saftflusse d. Laubbaume. Hedwigia, 1894, Bd. XXZIII,p.241. 

 Matruchot and Molliard, Variations de struct, d'une Algue 

 verte etc, , loc. cit, 



3. Ueb. farblose Diatomeen. Flora, 1901 (Erganaungsband) 

 Bd. LXXXIX, p. 404. 



4.Untersuch. uber d. Starkebildung in d. verschiedenar- 

 tigen Chromatophoren. Pringsheim' s Jahrb. f. wiss. Bot. 1898, 

 Bd. XXZII, p, 525. Compare also Frank, Krankh. d. Pfl., 2, 

 Aufl. Bd. I, p. 225, and other places. Zimmermann, Morph. u. 

 Phys. d. Pflanzenzelle, 1893. p. 31, 53; Timpe. loc. cit., 

 Pantanelli, Studi sull' albinismo vei regno vegetale. Mal- 

 pighia, 1902, Vol. XV, p. 353. 



4. Kocks, K. Beitr. z. Einwirkung d. SchildlEuse auf das 

 Pflanzengewebe. Jahrb. Hambur g. wi s s. Ana t.l 900 ;?Bd. XVII ,5oBeiheft 



5. Einfl, d. Lichtes auf d. herbstl. Verfarbung d. Laubes 

 Sitzungsber, Wiederrhein. Ges. Natur - u. Heilkunde-Bonn, 

 1891, p. 80. 



