T 



It is of much greater moment to know what is the largest 

 average number of worms which shall have attacked a " pickable " 

 ripe boll. The definition of a " pickable " ripe boll is : a pickable 

 boll is a boll of ripe cotton, such as would normally be taken when 

 harvesting the cotton. Unfortunately, it is not possible to be more 

 precise, and different people's idea of pickable will vary to some extent, 

 though probably not much. It will possibly also vary with the price 

 of cotton, and perhaps also become less conservative towards the end 

 of the season, when there is a smaller proportion of good cotton; it 

 may also vary annually. There is, however, considerable uniformity 

 in our samples of ripe cotton, which have been collected during 

 several seasons, and by very many different men. Some samples have, 

 however, been outstanding, much better or worse than the average. 



The probable average maximum number of worms in any one 

 pickable boll is about four, as will be shown shortly. This number 

 might involve half of the seeds in a boll of Sakellarides, and would 

 almost certainly require two locks if not all three to have been damaged 

 (see Table VI). On Table IV some of the main facts necessary to- is- 

 memberin connection with pickable bolls have been rawde/I. It.wiU. 

 be seen that the first column is entitled "apparent percentage,'' whilst 

 the second one is headed "true percentage." The apparent percentage 

 is the figure that would be obtained by examining a sample of ripe 

 cotton, picked in the ordinary way, i.e., with the exclusion of badly 

 damaged bolls, fallen bolls, etc. The true percentage would include all 

 bolls produced, whether good, bad or indifferent. Theoretically the 

 apparent percentage can be reckoned from Table I, by utilising only 

 those figures (at any percentage) which refer to bolls with from 0^4 

 worms. The proportion of attacked bolls to the total number of bolls 

 in the part sample gives the apparent percentage attack. There is no 

 difference between the select population and the total population until 

 15 per cent attack is. reached ; from there on the difference is at first 

 minute, but finally becomes enormous. Thus at 99 per cent true attack, 

 equivalent to about 80 per cent apparent attack, there are roughly 

 nineteen bolls in the total population outside the select sample to each 

 one within it. These bolls, which belong to the total population but 

 not to the select population, are pure loss, and represent mabruma 

 (i.e., bolls which have failed to open normally), and fallen bolls. The 

 number of worms within the select population per 100 bolls is given. 

 Compared with the figure on Table III, it will be seen that until 

 33 per cent attack is reached, the number of worms required per 100 

 bolls is the same for all possibilities we have considered. The final 

 number required for the special population of 0-4 worms per boll is, 

 however, very low in comparison. 



The following example, showing how the set of figures on Table IV 



