220 DR. PETTIGREW ON THE MECHANISM OF FLIGHT. 



Exp. 2. Detached posterior two-thirds of either wing in its long axis. Plight still 

 perfect. I confess I was not prepared for this result. 



Exp. 3. Detached one-third of anterior or thick margin of either pinion obliquely. 

 Might imperfect. 



Exp. 4 Detached one-half of anterior or thick margin of either pinion obliquely. The 

 power of flight completely destroyed. Prom experiments 3 and 4 it would seem that 

 the anterior margin of the wing, which contains the principal nervures, and which is the 

 most rigid portion of the pinion, cannot be mutilated with impunity. 



Exp. 5. Detached one-third from the extremity of either wing transversely, i. e. in the 

 direction of the short axis of the pinion. Plight perfect. 



Exp. 6. Detached one-half of either wing transversely, as in experiment 5. Plight 

 very slightly (if at all) impaired. 



Exp. 7. Divided either pinion in the direction of its long axis into three equal parts, 

 the anterior nervures being contained in the anterior portion. Plight perfect. 

 . Exp. 8. Notched two-thirds of either pinion obliquely from behind. Plight perfect. 



Exp. 9. Notched anterior third of either pinion transversely. The power of flight de- 

 stroyed. Here, again, the mutilation of the anterior margin was followed by loss of 

 function. 



Exp. 10. Detached posterior two-thirds of right wing in its long axis, the left wing 

 being untouched. Plight perfect. I expected that this experiment would result in 

 loss of balancing-power ; but this was not the case. 



Exp. 11. Detached half of right wing transversely, the left one being normal. The 

 insect flew irregularly, and came to the ground about a yard from where I stood. I 

 seized it and detached the corresponding half of the left wing, after which it flew away 

 as in experiment 6. 



I performed a series of analogous and not less remarkable experiments on the wings 

 of the Dra gonfly . 



Very similar results were likewise obtained from the House-sparrow, which is a heavy 

 bird, and by no means a powerful flier : 



Exp. 12. Detached the half of the secondary feathers of either pinion in the direction 



°1 l 1 ™^* 1 * ° f ! bG 7 ing ' ^ G P rimaries 1)ein S left intact. Flight as perfect as before 



quent experiments, one 



the mutilation took place. In this, as in many of the 



was operated upon before the other, in order to test the balancing-power. In the 

 present case the bird flew perfectly, either with one or with both wing. rat. 



Exp 13. Detached the half of the secondary feathers and a fourth of the primary ones 

 of either pimon m the long axis of the wing. Flight in no wise impaired. The bird, in 

 his instance, flew upwards of 30 yards, and, having risen a considerable height, dropped 

 into a neighbouring tree. 



o""""""n 



Etp. 14. Detached nearly the half of the primary feathers in the long axis of either 

 pmion, the secondaries being left intact. When one wing only was operated upon, 



faboureT '' ^ ^ ™° ^^ With ' «* Was stiU P erfect > but sU ^ 



&p. 15. Detached rather more than a third of both primary and secondary feathers of 



