678 



NATURE 



[January 20, 192 1 



■work of the University and some of the current inves- 

 tigations. Demonstrations were also given of the 

 use of the microscope for the study of crystallisation, 

 by Mr. T. V. Bariier, who had prepared a pamphlet 

 outlining a course of study suitable for schools, and 

 of glass-blowing by Mr. B. Lambert, who gave many 

 valuable hints on dealing with operations which are 

 constantly a source of difficulty in making apparatus. 

 All these demonstrations were repeated next day, and 

 the association is greatly indebted to the distinguished 

 University teachers who expended so much time and 

 care on them. 



A lecture on the control of growth was given by 

 Mr. J. S. Huxley. After explaining the charac- 

 teristics of the life-cycle of all animals, the lecturer 

 showed how the growing stage could be accelerated 

 or retarded by external conditions in the case of some 

 lower organisms, and illustrated cases where it can 

 be reversed. Two opposing processes may be dis- 

 tinguished, and by stimulating one or the other the 

 progress of the resultant change can be controlled. An 

 interesting case was related of an Australian soldier 

 whose mind, as the result of shell-shock, reverted to 

 the infantile stage, but, happily, on his return to 

 Australia it developed again to the normal condition. 

 Mr. Huxley went on to describe experiments with 

 mice, the average life of which had been extended 

 about 20 per cent, beyond the normal duration, and 

 the treatment of a rat which had its vouth restored 

 after reaching a state of marked spnility. In con- 

 clusion, the opinion was expressed that in the course 

 of time it would be possible to extend the duration 

 of man's life verv appreciablv. 



A lecture on indicators and the law of mass action 



was delivered by Brig.-Gen. Hartley. The lecturer 

 pointed out and illustrated the confusion resulting 

 from the idea of neutralisation, and showed that the 

 way to obtain a clear insight was to regard the 

 indicators as weak acids or bases (fortunately the 

 tautomeric changes need not be considered here) and 

 work quantitatively in terms of the hydrion concen- 

 tration from the known dissociation constants. Brig.- 

 Gen. Hartley illustrated this by making four sets of 

 solutions in which the hydrion concentration varied 

 by factors of lo from lo-' to io-'° (made by adding 

 to N/io acetic acid the calculated amounts of a solu- 

 tion of sodium acetate, as by this method the acci- 

 dental introduction of impurities does not seriously 

 alter the hydrion concentration), and adding to all 

 the members of each series methyl-orange, methyl- 

 red, phenolphthalein, and litmus respectively. It 

 was then evident between what limits of concentra- 

 tion the colour change occurs in each case. Graphs 

 were made showing the resultant hydrion concentra- 

 tion when various amounts of a particular alkali were 

 added to 25 c.c. of a given acid. From these graphs 

 it was at once evident what would be a suitable 

 indicator and how sharp the colour change would be. 

 Some further graphs showed the immense difference 

 that would result if the constant for water were to 

 have a different value. 



In a lecture on the Hedjaz Mr. D. G. Hogarth 

 gave an account of the geographical conditions and 

 a most interesting review of the political positions 

 since 1914 and their bearing on the war in the Kast. 



Throughout the meeting there was an exhibition 

 of apparatus and books by manufacturers and 

 publishers. 



Research on the Pink Boll-worm. 



THE pink boll- worm, the larval stage of the 

 Tineinid moth, Gelechia gossypiella, Saunders, 

 is responsible for considerable damage to cotton in 

 most cotton-growing regions, and its importance in 

 Egypt has led to an extensive 'Study of its habits and 

 of methods of control (H. A. Ballou, 1920, "The 

 Pink Boll-worm," Report of Ministry of Agriculture, 

 Egypt; L. H. Gough, iqig, "On the Effect Produced 

 by the Attacks of the Pink Boll-worm on the Yield 

 of Cotton-seed and Lint in Egypt," Agricultural 

 Journal of Egypt, vol. ix.). 



The pink boll-worm was first discovered in Egypt 

 in 1910, probably having been introduced in cotton 

 from India, and in 1912 it had attained a position of 

 first importance as a pest of cotton in that country, 

 and since that time it has been the principal pest 



of this crop. . „ . 



In its adult state Gelechia gossyptella is a small 

 moth with a wing-spread of between 15 and 19 mm. 

 The general colour of fresh specimens is coppery- 

 brown with blackish spots varying in size and inten- 

 sity. The eggs are laid on the green parts of the 

 cotton plant, and the larvae make their way to a boll 

 or bud, where they feed inside the developing seeds 

 or upon the ovules. When fully grown, the larva 

 measures 10 to 12 mm. in length, the pinkish colour 

 occurring in broad transverse bars on a yellow ground, 

 and may pupate in the boll or seed or enter the earth. 

 The larval state lasts from ten to nineteen days, but 

 late in the season the larva, instead of pupating when 

 full grown, may enter a resting stage, in which it 

 may remain for as long as thirty months. This is 

 the most important stage in the life of the insect, 

 and the principal effort at control is directed at the 

 larvae before and during this stage. 

 NO. 267?, VOL. I06I 



The pink boll-worm damages cotton-seed in the 

 boll, and its attacks result in reduced and weakened 

 lint and reduced seeds, which may be light in weight 

 and of low germinating power. 



Legislation has made it compulsory for all plants 

 to be pulled, and the remaining bolls destroyed, by 

 a certain date, which varies between December 15 

 and January 15 in different districts; it has enforced 

 the provision of approved machines for treating all 

 seed in the ginneries by heat or fumigation, and 

 made it compulsory for all stores containing cotton- 

 seed to be screened from May to .August to prevent 

 the escape of adults. 



The first campaign on a large scale against the 

 pink boll-worm was carried out in 1916, and aimed 

 at the destruction of resting larvse in the bolls left in 

 the field after the crop had been gathered. _ The 

 method which is recommended for the future is for 

 the cotton sticks to be removed from the field before 

 cleaning, taken to a central place, and there cleaned 

 by drawing through a comb or rake, no sticks to be 

 allowed into a village until all have been passed_ by 

 an inspector as clean, and the unclean sticks 

 destroyed. 



The picking of the crop should be as early as 

 possible, as the attack of the pink boll-worm is more 

 severe late in the season, and also the later larvae 

 are more likelv to pass into the resting stage by 

 which the infestation of the following year is 

 caused. 



Treatment of cotton-seed bv heat at a temperature 

 of from i;'^° to 73° C. was found to be effective 

 in destroving all resting-stage larvae, whjie having 

 little effect on the percentage of germination of the 

 seed. 



