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phenomena classed under the heading of antagonistic ion action 

 are apparently much more complex than has hitherto been 

 assumed, and it is necessary to apply exact physico-chemical 

 methods to the analysis of the various cases. True and Bartlett 

 (Amer. Jonrn. Bot. 2) have investigated in detail the exchange 

 of ions between lupin roots and culture solutions containing 

 respectively one and two nutrient salts ; the chief points 

 brought out are that when a mixture of corresponding salts or 

 two or three different metals is present, the roots usually absorb 

 more than from pure solutions of equal concentration, that in 

 pure solutions one metallic ion may be more favourable to 

 absorption than another in weak concentration, while in stronger 

 concentration the reverse holds good, and that absorption and 

 growth are more or less independent phenomena. Osterhout 

 (Bot. Gaz. 59), in continuing his studies of permeability, has 

 found that there is a remarkable difference between monovalent 

 and bivalent kations in their effects on permeability, none of 

 the former being able to decrease permeability, while all the 

 bivalent kations investigated did so to a marked degree ; and 

 that protoplasm is able to withstand very great changes of 

 permeability, an increase or decrease of 30 per cent, or more 

 being possible without rendering a return to normal permeability 

 possible. 



Pentose sugars, such as xylose and arabinose, are of general 

 occurrence, in the form of their polysaccharides, such as xylan 

 and araban, in the cell-walls of plants, and numerous investiga- 

 tions have been made as to their utilisation by both animals 

 and plants, though the question whether organisms secrete 

 enzymes capable of splitting the complex pentosans into their 

 constituent sugars has usually hitherto been answered in the 

 negative. Hawkins (Amer. Journ. Bot. 2) has studied the 

 action of a fungus, Glomerella cingulata, on these substances, 

 and claims to have obtained definite evidence that in this case 

 at any rate such an enzyme is present. The fungus was found 

 capable of utilising either glucose, xylose, arabinose, araban or 

 xylan as a sole source of carbon, the three sugars being most 

 efficiently utilised, xylose on the whole best, and it thrived 

 better on xylan than on araban. A filtered extract of the fungus 

 can act on xylan under aseptic conditions with the formation of 

 alcohol-soluble substance which reduces Fehling, forms furfurol 

 when boiled with HC1, and possesses other properties of xylose, 



