116 THE FUNCTIONS OF 



of calcium, but also containing boric acid, development was 

 very much better, and, although there was some blackening of 

 the leaves, the plants grew fairly tall, the stems did not blacken 

 and normal flower buds developed. Brenchley and Warington 

 interpreted these results as indicating that without boron the 

 plants were unable to absorb or utilize sufficient calcium to 

 prevent poisoning by the other nutrient salts, while when boron 

 is present the latter enables the plant either to absorb calcium 

 more rapidly or to utilize it more readily so that the toxic 

 effect of the other nutrients is antagonized. It may be noted 

 that in cultures without boron, as the supply of calcium is in- 

 creased the symptoms of calcium shortage become less marked 

 until with 0-1 g. of calcium sulphate per litre they disappear 

 and the plants show typical symptoms of boron deficiency. 



Later, Warington (1934), by actual determination of the 

 amount of calcium absorbed by plants growing in culture solu- 

 tions, showed that the presence of boron does indeed result in 

 a very considerable increase in the amount of calcium absorbed 

 by plants of Vicia Faba. The actual values she obtained are 

 summarized in Table XIII. 



Results comparable with those of Miss Warington have been 

 obtained with soya bean by Minarik and Shive (1939). Plants 

 were grown in sand cultures supplied with the usual major 

 nutrients and manganese. Boron was supplied to the different 

 cultures in concentrations varying from to 10 p. p.m. As the 

 results summarized in Table XIV show, the boron supply 

 definitely influenced the amount of calcium which accumulated 

 in the leaves, and that indeed the effect of boron on the growth 

 of the plants was parallel with its effect on calcium uptake. 



But this effect of boron in influencing calcium intake does not 

 appear to be general. Indeed, Holley and Dulin (1937), working 

 with cotton, could find no indication of a relationship between 

 boron and calcium, and Morris (1938) found no difference in 

 calcium content in normal and boron-deficient oranges, while 

 Talibli (1935) actually found that addition of boron to the 

 medium on which flax was growing brought about a reduction 

 in the calcium content of the flax straw. 



Work by Marsh and Shive (1941) on maize appeared to throw 

 some light on the apparent divergence between the results 



