NOTES AND ABSTRACTS. 



235 



remarkable plant are white with yellow centre, rather pretty, but they 

 only last a day. Ottelias can only be increased by seeds, and this is 

 rather difficult, as only about 8 per cent, seedlings survived. 



Aponogeton Dinieri, from South Africa, was first known under the 

 name of A. flavum. Since it flowered and was found to be a new 

 plant it was named after its discoverer. It resembles the common 

 A. distachyon, but has yellow flowers. Being less prolific than A. 

 distacliyo7i and more difficult to manage, this species is still very rare- 

 Echinodorus grandiflorus, another grand aquatic from South 



.America. It has large handsonde leaves and panicles of white flowers. 

 It easily ripens seeds, which can be preserved dry, and when sown in 



;the spring they germinate quickly and surely. — G. R. 



Ammonia in Soils. By Dr. E. J. Eussell {Jour. Ag(r. Set. iii. 

 ipt. 3, pp. 233-245, Sept. 1910). — The author discusses methods of 

 estimating ammonia in soils, 'and gives two based upon his observations. 

 The amount of ammonia in the soil is very small (about one or two 

 parts in the million of soil, rising to five or six in heavily dunged or 

 .garden soils), and remains fairly constant throughout the year. There 

 lis no tendency for ammonia to accumulate, since the rate of nitrification 

 lis greater than that of ammonia production. — F . J. C. 



Apple Orchards, The Fertilization of. By J. P. Stewart 

 (U.S.A. Exp. Stn., Pennsylvania, Bull. 100; June, 1910; 9 figs).— 

 'Fertilizers are but one of many factors that affect success in orcharding, 

 and their application may be wholly without effect in the presence of 

 weaker factors which are exercising a greater influence than the defici- 

 3ncy of plant food in limiting the crops. "When all other factors are 

 apparently right the need of fertilizers may be indicated by the trees 

 oeing deficient in growth, foliage, or fruit. In the experiments described 

 n this bulletin nitrogen has greatly increased the quantity of fruit, and 

 he author thinks that many failures with potash and phosphate have 

 3een due to a deficient nitrogen supply. It needs using cautiously, how- 

 ever, as it lessens the colour of the fruit and sometimes its size also. 

 Diminished colour following an excess of nitrogen is associated with 

 lelayed maturity and diminished light supply to the fruit owing to the 

 ncreased density of the foliage (p. 14). It has been found that apples 

 ixposed to sunlight after gathering developed increased redness by over 

 >5 per cent., while those kept in the dark showed practically no in- 

 Tease. None of the fertilizers applied has shown any consistent ability 

 0 improve the colour or the size of the fruit, the latter being held to 

 lepend upon the amount of moisture available. As regards crops 

 , ome very striking results are shown, increased yields valued at £30 to 

 '>50 per acre having been obtained as the result of manuring apple 

 rees, presumably in cases where plant food had previously been the 

 irop limiter in those orchards (p. 16). The results of the experiments 

 ?3ad the author to make a general recommendation of the use of 



