312 



phenomenon appeared in June after a longer period of intense drought and 

 became widespread especially in sunny positions and on light soils, while 

 regions with a damp, sea climate showed the disease only slightly. The sugar 

 content of the slowly growing beet was from 2 to 3 per cent, less than that 

 of healthy specimens. 



By a survey of the individual cases just cited, we are led to the con- 

 viction that icterus is one of the most widespread symptoms of disturbed 

 assimilation. No conclusion as to any definite cause has been furnished as 

 yet, however, in the occurrence of jaundice. 



h. Changes Due to a Lack of Phosphorus and Sulfur. 



The distribution of phosphorus in the various parts of the plant, de- 

 termined earlier by Ritthausen's macro-chemical studies, was proved later 

 micro-chemically by Lilienfeld and Monti, as well as by Pollacci'. The 

 last found that, in general, the ceil walls are free from phosphorus while 

 the proptoplasm, and especially the nucleus, with the chromatin bodies, con- 

 tain this element in abundance. Among the aleurone bodies the crystalloides 

 and globoids likewise contain phosphorus. The proteins depend especially 

 on the amount of phosphoric acid at hand and a lack of it will make itself 

 felt especially in the blossom buds and in the maturing of the seed. Accord- 

 ing to Nobbe's cultural experiments^, phosphorus does not seem to play any 

 part in the formation of the chlorophyll pigment ; — the foliage of oaks which 

 had stood for three years in nutrient solutions, free from phosphoric acid, 

 was still green. In other plants Nobbe ultimately observed that a deep 

 orange red color appears in the leaves and petioles. There is no production 

 of any new dry substance, or only a small amount. Moller"' observed in 

 *he needles of his pine seedlings a blue-red (dull violet) color due to a lack 

 of phosphoric acid. In two-year old plants the violet color tended more to 

 olive brown. 



In the reports on discoloration phenomena, which set in with a lack of 

 various nutritive substances, the results obtained with one plant species 

 cannot be applied to a different species, since discoloration is not every- 

 where the same. In regard to phosphoric acid, I found that when plants of 

 beets, peas, and seradella were grown without phosphoric acid they dried a 

 gray green when they had j-reviously been a faded green, but not yellow, 

 while, with a lack of nitrogen, the same species turned a pure quince yellow. 



Nobbe found a somewhat better development with a lack of sulfur in 

 the nutrient solution, yet his experimental plants scarcely attained half the 

 normal height and the yellowish green leaf blades exhibited a correspond- 

 ingly scanty development. The starch was scanty and small grained. Cell 

 division was considerably impaired. The forming of fruit either did not 

 take place, or only very scantily. 



1 Pollacci, G., Sulla distribuzione del fosforo nei tessuti veg'etali. Malpighia. 

 Vol. VIII. Cit. Zeitschr. f. Pflanzenkrankh. 1895, p. 299. 



2 Dobner-Nobbe, Botanik fiir Forstmanner. 4th Ed., p. 317. 



3 Karenzerscheinungen etc. Zeitschr. f. Forst- u. Jagdwesen, 1904, p. 74.'> 



