679 



The green leaves show, therefore, in contrast to the white spotted ones, 

 considerably greater amounts of dry substances, while in the latter the ash 

 constituents (as found universally where disturbances in nutrition make 

 themselves felt) form a greater percentage of dry substance. The nitrogen 

 content in the white leaves of the ivy and the holly was greater in propor- 

 tion to the dry substance. This result is also expHcable ; for, if the chloro- 

 phyll apparatus, without doubt necessary for the production of starch 

 grains and other carbohydrates, is only scantily present, the amount of dry 

 substances is reduced and the absolutely smaller amount of substances con- 

 taining nitrogen appears relatively increased. The fact that the substances 

 soluble in alcohol and ether in the white leaves of ivy and holly amount to 

 about half that in the green leaves likewise may not be considered surprising. 



The percentages in the composition of the ash are very important. 

 They are as follows : — 



Acer Ilex Hedera 



white green white green white green 



per cent, per cent, per cent, per cent, per cent, per cent. 



Potash 45.05 12.61 35.30 16.22 47.20 17.91 



Lime 10.89 39-93 21.50 34.43 12.92 48.55 



Magnesia 3.95 4.75 3.23 2.43 i.ii 1.04 



Phosphoric acid... 14.57 8-8o 9.51 7.29 10.68 3.87 



Iron oxide ? ? 3. 11 3.11 2.62 2,31 



It .is evident from these figures that organs without pigmentation 

 approximate the condition of young green leaves and have, therefore, failed 

 to develop in a normal manner. Griffon^ has come to the conclusion that 

 plants without pigmentation behave in general like etiolated ones, which we 

 have also compared to arrested development. In the yellow transitional 

 stages the results of variegation are very different. In Abutilon Thomp- 

 soni I found the cell content in many leaves still arranged as in perfectly 

 green parts, i. e., provided with chloroplasts, their edges roundish angular, 

 which were normally arranged against the walls but were a pale yellow, or 

 colorless, and had a strongly granulated content. In other cells the sub- 

 stance of the chloroplasts was united into irregular Agranular balls which 

 took on a blue color with iodine, glycerine, and in part also with sulfuric acid 

 and which might be called carotin. KohP also found carotin (etiolin), in 

 the investigation of golden yellow leaves, besides ;^-zanthophyll and 

 phyllofuscin. 



The difference in the thickness of the leaf, i. e., the noticeably lesser 

 thickness of the pure white parts in contrast to the pure green parts, 

 decreases the more the color tone varies from the pure white ; i. e., the more 

 yellow the places in the leaf become. Timpe^ also calls attention to this 



1 Griffon, Ed., L'assimilation chlorophyllienne et la coloration des plantes. 

 Annal. sc. nat. VIII, 1899; cit. Bet. .Jahresber. 1899, I, p. 151. 



2 Kohl, F. G., Untersuchungen iiber das Carotin und seine physiologische 

 Bedeutung in der Pflanze. Leipzig-, Borntrager, 1902, IX. 



3 Timpe, H., Beitrage zur Kenntnis der Panachierung. -Dissertat., Gottingen, 

 1900. 



