43 



necessary. With regard to the minimum temperature that is fatal 

 to the larvae and injurious to the seed, Table II gives a similar set of 

 figures for the germination of treated cotton seed to those given in 

 Table I for the mortality of the caterpillars. The results indicate that 

 proxnded neither the whole mass of seed nor individual seeds are 

 heated to a higher temperature during the treatment, wet seed can 

 safely be raised to a temperature of 140° F., and dry seed to a 

 temperature of at least 150° F. without affecting germination. More- 

 over, seed at these temperatures can safely be sacked in spite of the 

 slow cooling of cotton seed in bulk. Questions regarding the 

 controlling of the temperature during treatment are discussed. 



The machines considered in detail are classed as follows : — 

 (1) Machines in which the seed is heated by a current of hot air. These 

 include the Ministry of Agriculture's hot-air machine [see this Review, 

 Ser. A, iv, p. 472] ; the Hess Drier, which is a modification of an 

 American machine used for conditioning maize, and which, while 

 being the most economical of all to run, promises, with slight modifica- 

 tions, to prove satisfactory. The Neumancantelli hot-air machine is 

 an ingenious device consisting of six cylinders on a revolving base, 

 which at definite intervals is moved round automatically until each 

 cylinder occupies the position held previously by the one next to it, 

 so that the seed is treated in six stages. Unfortunately, it was found 

 impossible in practice to get a sufficiently rapid current of air to raise 

 the temperature of the seed at a reasonable pace. The inventor of this 

 machine has since submitted another design, in which the seed is 

 passed do\vn a series of revolving discs and travels from the 

 centre to the circumference of each, passing altogether over a 

 distance of 40 to 45 metres on the surface of the discs. No machine 

 of this kind has been completed, but it seems probable that, in its 

 present form, the seed may remain too long in direct contact with, the 

 steam-heated surface of the discs and thus become damaged. 



(2) Machines in which the seed is heated by radiation from steam 

 pipes. These include the Domains' machine [see this Review, Ser. A, iii, 

 p. 505], and Matsouchis' (Planta's) machine, consisting of a series of 

 long axles with radiating blades, arranged one above the other, alternate 

 axles revolving in opposite directions. During its j ourney from blade to 

 blade the seed is heated by radiation from steam tubes. This machine 

 is not yet completed : the heating by radiation should involve less 

 danger of overheating individual seeds, but a disadvantage lies in the 

 necessity for a very much larger heating surface for the same output. 



(3) Machines in which the seed is heated by direct contact with 

 metallic heating surfaces. These include Simon's machine [see this 

 Review, Ser. A, iv, p. 491] ; Lenzi's machine, which is the simplest 

 form of seed-heating, consisting of a long, narrow cylinder, steam- 

 jacketed all round, in which revolves an axis with propeller blades 

 that force the seed from one end to the other. Seed treated at 132° F. 

 showed complete mortality of the larvae, but about 5 per cent, of 

 the seed was damaged, probably by too long contact with the heating 

 surface. By keeping the seed in more rapid motion this defect should 

 be remedied and the machine found satisfactory. Macri's machine, 

 which is very similar to the above, gave satisfactory results, though 

 some minor improvements are recommended. Baker's machine is also 

 similar, but the cylinders through which the seed passes, instead of 



(C412) a2 



