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in a series of tables. The use of highly inflammable and poisonous 

 gases is deprecated, owing to the necessity for employing ignorant 

 native labour. Carbon dioxide and sulphur dioxide have both been 

 proved to cause a loss of vitality in the wheat, while both of these 

 gases are useless as asphyxiating agents, owing to the ability of the 

 insects to enter a state of hibernation in the absence of oxygen. 

 Moisture and dryness have been considered important factors in control, 

 but while desiccation is an effective remedy against C. oryzae, 

 A. wndulatus seems to prefer dry conditions to moist ones, while 

 R. dominica is apparently indifferent to either. 



Chemical deterrents, such as naphthaline, have been found successful 

 in the case of stored maize [see this Review, Ser. A, ii, p. 204], but while 

 wheat may be preserved for seed purposes by this means, it cannot 

 afterwards be sold for food, owing to the objectionable taste and odour 

 it acquires. 



Mechanical separation of weevils from the wheat has been proved by 

 scientific enquiry to be the best and most efficient method. This is 

 often done by means of a sieve in the Punjab villages. The adults 

 of R. dominica and C. oryzae can easily be sifted out, but the larvae of 

 A. undulatiis must be removed when young, or better still in the egg 

 stage. A mechanical treatment is therefore necessary which will 

 combine the advantage of sifting with those of a density separation, 

 any substances which are of less density than undamaged wheat being 

 " floated out." The damaged grain will be proportionately lighter 

 according to the amount of endosperm eaten away, and will be carried 

 away by a current of air more easily than sound grains. The separator 

 designed by the authors consists of a tube, in this case constructed of 

 thin sheet iron, mth a number of bends, each at an angle of 40° with the 

 perpendicular, the object being to neutralise the increasing momentum 

 of the falling grain due to gravitational acceleration. With a sufficiently 

 long tube, divided into a sufficient number of steps, a uniform velocity 

 can be obtained for the falling grain. An air-blast sent up the tube 

 at an increasing velocity will reach a point when its momentum is 

 equal to that of the falling grain. At this point the grain will " float." 

 Inunediately below each bend of the tube there is an egress port ; at 

 each of these a portion of the uprushing current of air escapes carrying 

 with it all matter that is light enough to " float " in it. The amount 

 of air escaping at each port will be less as it travels higher in the tube, 

 so that at the top of the tube only the lightest materials, insects, dust, 

 detritus, etc., are removed. The grain still travelling down the tube 

 meets an increasingly stronger current of air and the heavier damaged 

 materials are blown out ; first dust, then shells and then the more or 

 less damaged grain. When this method is used, by-products of varying 

 value can be collected from the various egress ports. 



After a prehminary cleaning by this process, a number of eggs are 

 likely to be left attached to the epidermis of the wheat. A second 

 cleaning should therefore be undertaken as soon as sufficient time 

 has elapsed for the adult insects to emerge without having ovi- 

 posited. Such wheat should be stored in bins or chambers sa 

 constructed that there are no cracks or corners in which insects can 

 lodge. 



This paper contains a large amount of detail unsuitable for an 

 abstract and should be read in the original by those interested. 



