﻿444 BOTANICAL GAZETTE [JUNe 



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somes, individuality of the chromosomes and morphological organization of 

 the nucleus, and the determination of sex. The theory that the chromosomes 

 are permanent organs dominates the entire philosophical portion of the 

 paper, and the evidence in favor of this theory is ably presented. — Charles 

 J. Chamberlain. 



Newcombe^*^ has shown conclusively that the so-called thigmotropic 

 responses obtained by Sachs in terrestrial roots were not really such, but 

 merely the effect of injury. The primary roots of seedlings of Zca mays, 

 Pisum sativufn, Phaseohts vulgaris, and Vicia faba were tested for thigmo- 

 tropic curVatures with pins, pieces of brass wire, glass needles, and splinters 

 of white oak, yellow and white pine, and tulip wood. None of the species 

 exhibit curvatures with glass or tulip wood and none but Vicia with white 

 pine, but they all curve in the manner described by Sachs when in contact 

 with metal or yellow pine. These observations destroy the only remaining 

 evidence of thigmotropism in terrestrial roots. The phenomenon may be 

 regarded as established, however, for aerial roots. In another paper^^ the 

 same author has shown that in rheotropically curving roots of Brassica alba, 

 Fagopyrum escidentum, Helianthiis annuiis, 3.ndZea mays (yvhite pop corn) ^ the 

 sensory zone extends upward from the tip beyond the region of growth. The 

 same fact was already proved by the same author in case of Raphanus sati- 

 vus,^^ Brassica alba shows good rheotropic curves when the root tip is 

 shielded from the water for a distance of 25 "'"^ although the region of 

 growth extends back from the tip only 5 or 6'"™. The other roots shovt^ simi- 

 lar results. — Burton E. Livingston. 



Gerneck's''^ experiments with wheat, oats, maize, and cress in various 

 solutions of single and combined salts yielded the following main results. 

 Of the single solutions, several chlorids, potassium phosphate, and water favor 

 the development of stems rather than leaves, while the reverse is true of 

 nitrates and sodium sulfate. Chlorids of the alkaline earths give stronger 

 plants than those of the alkaline metals. Ca(N03)2 produces dwarf plants 

 with very hairy leaves and roots. The fewest hairs appear on plants with the 

 strongest leaves. The most chlorophyll occurs in KNO3 cultures. With com- 

 plex solutions wheat can endure the addition of 1.5 per cent,, cress i per 

 cent, and maize 0.5 per cent. NaCI to the nutrient solution. The addition of 



^^Newcombe, P\ C, Sachs' angebhche thigmotropische Curven an Wurzeln 

 waren tratnnatisch. Beih. Bot. Centralbl. 12 : 243-247. 1902. 



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^^Newcombe, F. C The sensory zone of roots. Ann. Bot. 16: 429-447- fis- -^• 



1902. 



ao 



-, The rheotropism of roots. BoT. Gaz. 33 : 177- 19^1 263-283 



341-362. igo2. 



" Gerneck, Rudolph, Ueber die Bedeutung anorganischer Salze fiir die Entwick- 

 lung und den Bau der hoheren Pflanzen. Inaugural-Dissertation, pp. I47- Gottin- 

 gen: W. F. Kaestner. 1902. 



