468 SNAKES OF CEYLON. 



any one walked along in &e near neighbourhood. I had a 

 kerosine oil tin at hand, and when the snakes were recumbent 

 I beat this with a stick close to their heads without their 

 taking any notice whatever. Similarly, I blew a bugle close 

 beside them, but they were not charmed ! The greatest care 

 is necessary in conducting such experiments to eliminate all 

 other possible means of rousing the snake. For instance, if 

 a rusty tin is beaten over the snake, particles will fall on it 

 and rouse it to attention. Similarly, if the blast of air emitted 

 from the bugle, impinges ever so little on the snake, it is 

 roused to action and erects itself. 



Many people suppose that a snake is deaf, but this is not 

 the case. Snakes hear well, though they have no external 

 ears. Many people are not aware that there are two ways in 

 which the essential auditory apparatus may be stimulated 

 and sounds heard. If one strikes a tuning fork, and places 

 the stem on any part of the skull, or even the spine to its 

 lowest part, the vibrations can be heard distinctly. If the 

 head is in contact with a table, and the tuning fork struck, the 

 sound is audible when the stem is placed on the table at some 

 distance though inaudible when not touching the table. This 

 is due to the conduction of vibrations through solids, and 

 such vibrations are better heard and for a longer time, than 

 those conducted by waves of air, which strike upon a membrane 

 (the drum), situated at varying depths (according to the 

 particular animal) in a canal in the skull (the external auditory 

 meatus). The drum set vibrating acts through a chain of 

 tiny bones in the middle ear, so as to affect fluid contained in 

 semi-circular canals in the internal ear, the fluid in its turn 

 communicating the vibrations to highly specialized sense 

 organs at the termination of the filaments of the auditory 

 nerves. These nerves carry the impulses received to the 

 brain centres, where they are interpreted as sounds. This 

 latter method of conduction, viz., by means of the air, is the 

 predominating one in mammals, birds, and many reptiles, 

 but is entirely wanting in all snakes, there being no external 

 orifice, and no drum to receive impressions. Conduction by 

 solids is, however, good in snakes, perhaps for all we know 

 more highly sensitive than in man. 



