170 METABOLIC HORMONES 



results in failure of ovarian growth (Part II, § 4), castrated females 

 were also compared with mock castrated females, in which the 

 abdomen was opened and the viscera were disturbed but the 

 ovaries were left intact. The oxygen consumption of these controls, 

 expressed in relation to live weight, showed no significant differ- 

 ence between either the normal males and females or the castrated 

 and mock castrated females. In each group, estimations of oxygen 

 consumption were made at 25 °C on about 60 unanaesthetized 

 flies, tested individually every 10 min over a period of 2 hr. 



The mean uptake of oxygen for all readings was expressed as 

 mm^ O2/IOO mg fly/ 10 min for each fly. The results were graphed 

 (Figs. 5-1 and 5-2) to show the percentage of the total test group 

 having their mean value within each range or class interval ; they 

 were also tested statistically for significance. Only a few results 

 were rejected on the grounds that the flies were abnormally active 

 during the experiment and depleted the oxygen supply. 



To test the effect of allatectomy, the corpus allatum was removed 

 from about 150 flies within 7 J hr of emergence from the pupa. 

 The completeness of the operation was checked 7 days later, at 

 the end of the experiment, by examining the ovaries. If these 

 showed any appreciable growth due to corpus allatum stimulation, 

 results from that fly were rejected. 



In severity and duration, the control operation for allatectomy 

 was, as nearly as possible, the same as the real operation, without 

 actually damaging the corpus in any way. Mock-operated controls, 

 compared with normal females, showed that the operation caused 

 a drop in oxygen consumption, from 28-3 + 0-9 to 27-9 + 0-9 

 mm^ O2/IOO mg/10 min; but removal of the corpus allatum 

 reduced the mean for the three lowest values to 21-3 + 0-9 mm^ 

 (Fig. 5-1). Taking all values (25 out of 26 flies) into consideration, 

 the drop in oxygen consumption following removal of the corpus 

 allatum amounted to 16 per cent; this is statistically significant 

 (Thomsen and Hamburger, 1955). 



Re-implanting corpora allata from other flies of similar age and sex 

 into allatectomized flies was too severe an operation ; but implanta- 

 tion of 3 corpora into normal females was carried out. These flies 

 were compared with otherwise normal controls into w^hich tissue 

 other than corpus allatum was implanted. Survival was reasonable. 



