312 



DR. L. H. GOUGH. 



Middle and Upper Egypt. In figure 6 this information has been used to show 

 diagramatically the comparative moment when the 75 per cent., the 50 per cent, and 

 the 25 per cent, sound boll positions were passed. 



The following Table (XXI) shows how closely the figures for Gemmaiza agree 

 with those for the whole Delta. 



Table XXI. 



Comparison of Percentage of Sound Bolls from Gemmai 

 from the whole Delta. 



za and 





Week 



1 



2 



3 



4 



5 



6 



7 



8 



9 



10 



11 



12 



13 



14 



15 



16 



17 



18 



Delta 

 Gemmaiza 



98 

 100 



95 



100 



91 



97 



90 

 94 



87 

 94 



87 

 92 



87 



87 



85 

 86 



80 

 73 



72 

 63 



67 

 61 



51 

 43 



35 

 22 



22 

 14 



16 

 9 



8 

 2 



5 



— 



"Week 1 commenced 9tk June. 



B. Observations on Resting Larvae. 



An attempt has been made to solve the problem whether " resting " larvae feed. 

 Obviously this cannot be done by direct observation. For this reason sets of samples 

 of 100 larvae were weighed at various dates during 1917. The results are shown 

 in Table XXII, from which it will be seen that the weight has been found constantly 

 falling from February to July. The difference between the samples of the 2nd and 

 10th June is not significant. The fall in weight does not necessarily demand the 

 explanation that the larvae were fasting,but taken along with the known fact that 

 many hibernating or aestivating larvae do not feed, it lends considerable weight to 

 the probability of the larvae not feeding during their resting period. 



Table XXII. Weight of Sets of 100 Hibernating Gelechia Larvae. 



1917. 



Number of Sets. 



Average Weight. 



January 



3 



6 



2-483 ± 0-068 



February 



3 



10 



2-510 ±0-019 



March 



8 



6 



2-457 ± 0-068 



April 



2 



10 



2-403 ± 0019 



99 



7 



10 



2-369 ±0-019 



>> 



28 



10 



2-309 ± 0-019 



May 



8 



10 



2-286 ± 0-019 



99 



12 



10 



2-295 ± 0-019 



99 



19 



10 



2-304 ± 0-019 



>> 



26 



10 



2-262 ± 0-019 



June 



2 



10 



2-245 ± 0-019 



>> 



10 



10 



2-247 ± 0-019 



99 



16 



10 



2-099 ± 0-019 



J? 



24 



10 



2-093 ± 0-019 



July 



2 



8 



2-017 ± 0-021 



The agreement between the two sets of percentages is extremely close ; the 

 Gemmaiza figures begin a trifle higher and fall a trifle lower (perhaps not significantly) 

 than the combined Delta figures. The table shows that the bias in sampling for the 

 provincial samples was not great. The shortened crop season as compared with 

 that of the whole Delta requires no comment. 



