September 5, 1918] 



NATURE 



England and Scotland, as stated, but by twenty-eight 

 •countv councils in Scotland alone, and this also has 

 been the case for more than ten rears. 



\Vm. Eagle Clarke. 

 The Royal Scottish Museum, Edinburgh. 

 August 26. 



A Mistaken Butterfly. 



The following observation will be of interest in 

 ■conneclion with those related in Nature, vol. xcv., 



i9 r S- 



At Pennant Hills, near Sydney, on March 24 last, 

 1 noticed an interesting case of colour-attraction for a 

 butterfly. A lady was standing talking to two other 

 persons on the footpath opposite m\ house. Shi 

 wearing a plain brown straw hat, fixed with a hat- 

 pin having a light blue porcelain knob about half an 

 inch in diameter. A butterfh (Papilio sarpedon) kept 

 living about the knob as if fascinated, and followed 

 the lady closely when she went up the footpath to tin- 

 house, thing away only when the lath' entered the 

 house. 



I watched it for quite five minutes, during which 

 time the butterfly never went more than a few inches 

 from the lady's head, and always returned to the blue 

 knob, apparently trying to alight thereon. The lad} 

 several times brushed at the insect with her hand to 

 drive it away. Thos. Steel. 



Sydney, New South Wales. 



FERTILISERS AFTER THE WAR. 



IN view of the great increase in the facilities for 

 making sulphuric acid, attempts have natur- 

 ally been made to find an outlet for the new pro- 

 duction after the war, and a Departmental Com- 

 mittee appointed to go into the subject has re- 

 cently examined the possibility of an additional 

 production of fertilisers, which before the war 

 absorbed some 60 per cent, of the acid made. 

 The' report of the Committee (Cd. 8994, 1918) has 

 already been discussed in these columns from the 

 point of view of sulphuric acid production : it re- 

 mains now to consider the effect on fertilisers. 

 The report is very short and does not include the 

 statistical data necessary for a full discussion of 

 the problem : fortunately these can be collected 

 from other sources. 



Prior to the war the total consumption of arti- 

 ficial fertilisers in this country 7 was something 

 above 1,000,000 tons per annum, made up ap- 

 proximately as follows : — 



Farmyard manure 



Nitrate of soda 

 Sulphate of ammonia 

 Cvanamide (nitrolim) and nitrate 



of lime 



Superphosphate ... 



Basic slag ... 



Guano ... ... ... S; 



Bones ... ... ... , 



Others 



Total 



1,105,000 ... 4,540,000 



1 be made of the amount of guano, bones, and other 



Is used as fertilis 



NO. 2549, VOL. I02] 



At the same time the areas under the various 

 crops in the United Kingdom were as follows : — 



Wheat, barley, oats 

 Potatoes ... 



Swedes, turnips, mangolds 

 Other arable crops 

 Temporary grass 

 Permanent grass... 



Total 



1 the United 

 Kinedom 



7-67 



121 

 2-28 



' 55 

 661 



27 35 

 46-67 



This distribution of kind and consumpl 1 



Total ... 1223 12-8 144-8 22-3 120 



The experience of the war has shown that this 

 type of production is not really the most satis- 

 factory to the nation as a whole, as it leaves us 

 far too dependent on foreign countries for supplies 

 of wheat. On the other hand, a system of hus- 

 bandry that produces much wheat is unsatisfactory 

 to the' farmer because of the possibility that heavy 

 crops in the Argentine or North America or else- 

 where might pull down prices to unremunerative 

 levels. The risk may, in fact, never materialise, 

 but it has been burned into the farmers' minds 

 by the low prices of the nineties of the lasl 

 century. In consequence, before the war wheat- 

 growing was diminishing in this country, and 

 grass was increasing. 



Under the double stimulus of high prices and 

 Government action farmers have during the 

 war broken up more than 3,000,000 acres of gi 

 land and thus added considerably to the area 

 under cereals, particularly wheat and oats. The 

 breaking up of the grass land has led to the pro- 

 duction of much more food in the country and 

 necessitated the use of more fertilisers. I 

 officially stated that we now produce breadstuff s 

 sufficient for forty weeks per annum, whereas 

 before the war we produced only enough for ten 

 weeks. This does not, of course, mean that we 

 produce four times as much food as formerly ; 

 the breadstuff's are not quite the same as they 

 were ; but it does show that we go a long way 

 towards feeding ourselves. 



The scientific problems involved are more 



