174 Professor WiUiain Stirling [May 12, 



pulled up beneath its body, a position which no human eye ever saw 

 or artist depicted. The artist represents what he sees, and the 

 spectator demands that what is depicted shall correspond to what he 

 himself can see in a moving object. The sensitized film of the 

 camera fixes phases of movement that the eye is not sensitive enough 

 to distinguish. But fuse these apparently impossible poses by means 

 of a cinematograph, and one realises what relatively feeble analytical 

 powers the eye possesses as compared with a moving sensitized film 

 of celluloid in the cinematograph camera. 



Brief Notes on the Films. 



M. Gaumont 



The cinematograph films which I liave the honour of showing 

 you to-night were made expressly by " The Gaumont Co., Ltd.," to 

 illustrate the value of cinematography in biology, physiology, and 

 allied sciences. I desire to express publicly my best tlianks not only 

 to " The Gaumont Co., Ltd.," but also to M. Gaumont himself, who 

 has taken a kindly scientific interest in the production of these films. 

 Without his assistance I could not have undertaken this lecture 

 to-night. Nor do I forget what I owe to my old friend Professor 

 Fran9ois-Frauck, of the College de France, the successor of the late 

 Professor Marey. 



Artificial Amoeba. Amonhoid Movements and Surface Tension. 



Many attempts have been made to explain the amoeboid move- 

 ments of protoplasm manifested by an amoeba or by colourless blood 

 corpuscles, as being due to purely physical conditions, more especially 

 to variations of surface tension, a view associated with the names of 

 Quincke, Biitschli, and Rhumbler. In 1878 Gad made the following 

 experiment on surface tension. He placed a drop of rancid oil on a 

 dilute solution of carbonate of soda. The fatty acid acts on the oil 

 and a soap is formed : this lowers the surface tension at various points 

 of the drop of oil, and as a result the oil drop changes its form and 

 sends out and retracts processes having a superficial resemblance to 

 the pseudopodia of amoeba. This may be called an " Artificial 

 Amoeba." 



Rhumbler made the following ingenious experiment, to indicate 

 how, in his opinion, an Amoeba can take into its body and there coil 

 up a filamentous alga, as figured by Leidy in his magnificent work 

 on the Phizopoda. A drop of chloroform placed in water takes in and 

 coils up within itself a thin hair-like filament of shellac. 



Glohide of Mercury Pulsating like a Heart. 



When a metallic needle is brought in contact with mercury placed 

 in a watch-glass and the mercury is covered with a dilute solution of 



