DR PETTIGREW ON THE PHYSIOLOGY OF WINGS. 333 



transfixing the abdomen of insects with a fine needle, and watching the wings 

 vibrate against a dark background ; by causing dragon-flies, butterflies, blow- 

 flies, wasps, bees, beetles, &c, to fly in a large bell jar, one side of which was 

 turned to the light, the other side being rendered opaque by dark pigment ; 

 by throwing young pigeons and birds from the hand into the air for the first 

 time ; by repeated observation of the flight of tame and wild birds ; by stiffen- 

 ing, by tying up, and by removing portions of the wings of insects and birds ; 

 by an analysis of the movements of the travelling surfaces of quadrupeds, 

 amphibia, and fishes ; by the application of artificial fins, flippers, tails, and 

 wings to the water and air ; and by repeated dissections of all the parts directly 

 and indirectly connected with flight. 



Professor Marey obtained his results by gilding the extremities and mar- 

 gins of the wings of the insect with minute portions of gold leaf; by the 

 application of the different parts (tip and anterior margin) of the wing of the 

 insect to a smoked cylinder rotating at a given speed, the wing being made to 

 record its own movements ; by the captive and free flight of birds, which carried 

 on and between their wings an apparatus which, by the aid of electricity, regis- 

 tered the movements of the wings on a smoked surface, travelling at a known 

 speed in a horizontal direction ; and by the employment of an artificial wing, 

 constructed on the plan recommended by Borelli, Chabrier, Straus-Durck- 

 heim, Girard, and others. 



Professor Marey describes and figures a captive insect (the wasp) with its 

 wings forming figure of 8 loops/"" and a free insect, with its wings describing a 

 waved track, t precisely similar to what I described and figured in a variety of 

 ways in my memoir. J He also shows that the tip of the wing of the bird, 

 because of its alternately darting out and in during extension and flexion, 

 describes an ellipse. This, curiously enough, is another of the many points in 

 which I have anticipated this author, and one which I took special pains to 

 establish, § having in my memoir devoted no less than ten figures || to its illus- 

 tration. Professor Marey's views may therefore be regarded as confirmatory 

 of my own, as the following brief passage, selected from one of his j)apers, will 

 show. He writes : — "But if the frequency of the movements of the wing vary, 

 the form does not. It is invariably the same — it is ahvays a double loop — a 



* Revue des Cours Scientifiques de la France et de l'Etranger, 13 Fevrier 1869, page 175, figure 

 5. Professor Marey represents the wing of the wasp as fanning the air in a vertical direction. In 

 reality, the wing of the wasp and of most insects is made to vibrate very obliquely, and in a more or 

 less horizontal direction. 



f Revue des Cours Scientifiques et de la France et de l'Etranger, 13 Fevrier 1869, pages 173, 

 174, and 176. 



\ Trans. Linn. Society, Vol. XXVI, page 233, Diagrams 5 and 6 ; page 249, Diagrams 14, 15, 

 and 16 ; Plate XV. figures 59 and 61. Vide introduction to present memoir. 



§ Op. tit., pages 247, 248, 249, and 250. 



|| Op. at, pages 248 and 249, Diagrams 7, 8, 9, 10, 11, 12, 13, 14, 15, and 16. 



VOL. XXVI. PART II. 4 R 



