Amino-Acids and Rooting of Cuttings

Doak, B. W.

doi:10.1038/144379a0

Cited by 2 publications

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“…22]. In attempts tn determine which factors are supplied by leaves in the rnnting of cuttings Doak (9) demonstrated that a mixture of aminn acids promoted root formatinn in Rhododendron and later van Overheek et al (27) found that arginine and serine were hnth et'tVctive in ])r(>mnting rnoting nf leafless liitnscns cuttings. Sharp differentiation hetween ront initiation and development was nnt made by these wnrkers.…”

Section: Discussionmentioning

confidence: 99%

Studies on the Growth Factor Requirements of Pea Roots

Naylor

Rappaport

1950

Physiologia Plantarum

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Section: Discussionmentioning

confidence: 99%

Studies on the Growth Factor Requirements of Pea Roots

Naylor

Rappaport

1950

Physiologia Plantarum

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“…The use of cadmium hydroxide as a deproteinizing agent has been found very effective both for blood (17) and for plant extracts (18) and is said to eliminate all the 'residual reductidn' compounds. Blackwood(13) applied the method to obtain a 1:10 protein-free dilution of milk.…”

Section: (D) Polarimetric Methodsmentioning

confidence: 99%

279. The estimation of lactose in milk

McDowell¹

1941

Journal of Dairy Research

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THE estimation of lactose in milk by copper reduction methods gives results which are usually somewhat lower than those obtained by the polarimetric method. An adequate explanation of this discrepancy is still lacking. Recent work(i,2,3) has shown that a second sugar, probably glucose, is present in milk, but the proportion is very small and would not account for the differences in the lactose percentages obtained by the two methods. The present paper reports an examination of several of the methods of lactose estimation. METHODS (a) Volumetric copper reduction methodsThe direct volumetric copper reduction method of Lane & Eynon(4) may be applied to milk, as they suggest, by adding the milk, diluted 1:10, from a burette to the boiling alkaline copper solution. Carried out in this way the method is rapid and gives concordant results. It may be still further simplified, however, so that dilution of the milk and filling of the burette with each diluted sample is eliminated. The milk under examination (3 or 3-5 ml.) and also 30 ml. of water are added to the measured quantity of alkaline copper solution and the titration is completed by the addition of 0-5 % lactose solution from a burette. For the final accurate titration the 0-5 % lactose solution is run in to within 0-5 ml. of the end-point before boiling is commenced.Comparison of results for lactose content obtained by direct titration with results obtained after deproteinization. Clarification of milk with dialysed iron (5) gives a filtrate of the same pS. as the milk and free from the deproteinizing agent, but the dialysed iron does not remove calcium. As it has been shown that calcium salts cause a decrease in the amount of copper reduced(6,7,8) a further treatment of the dialysed iron filtrate with potassium oxalate becomes necessary. Table 1 gives results showing the effect of clarification with dialysed iron and of subsequent decalcification on the lactose estimation by the volumetric copper reduction method. It will be seen that treatment with dialysed iron results in a lower value for .lactose content and that this effect is largely eliminated by the decalcification with oxalate.Farmer(9) modified Lane & Eynon's method to include a clarification of the milk with lead acetate and sodium fluoride which remove both the protein and the calcium. The effect of clarification of milk samples by Farmer's method is shown in Table 2. There was no appreciable difference in the results except

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Amino-Acids and Rooting of Cuttings

Cited by 2 publications

References 0 publications

Studies on the Growth Factor Requirements of Pea Roots

Studies on the Growth Factor Requirements of Pea Roots

279. The estimation of lactose in milk

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