Rattle o/Crotalus durissus. 57 



snakes. Probably the snakes were kept under conditions 

 unfavourable for their welfare, whereby the vital processes 

 were checked. Perhaps, too, the observations were not con- 

 ducted with sufficient care. 



As regards the actual rattling, I can in general confirm the 

 words of Geyer : if the Rattlesnake is crawling slowly along, 

 it draws its rattle after it quite quietly along the ground ; if, 

 however, it is endeavouring to escape, it raises the rattle at an 

 angle of about 60°, and at the same time rattles continuously. 

 When the snake is in pursuit of its prey, nothing is usually 

 to be heard of it. This is not always the case, how- 

 ever ; on the contrary, I often saw Rattlesnakes pursuing the 

 rabbits which served them for food and makina; a loud 

 rattling, whereat, however, the latter showed no fear at all. 

 When irritated the Rattlesnake assumes the threatening 

 attitude which is admirably represented in Brehra's ' Kriech- 

 thiere ' (p. 492), and is at the same time capable of rattling 

 literally for hoars and continuously. The noise which it 

 thus produces can be with difficulty compared with any other • 

 in any case it only very distantly resembles the " chirping of 

 a grasshopper," as is asserted by Brehm. A large powerful 

 Rattlesnake makes so loud a noise with its rattle that it is 

 impossible to understand the words of a person speaking in a 

 loud tone at a distance of three paces when the snake's cage 

 happens to be between the individuals conversing. The 

 powerless specimens which we usually see in zoological 

 gardens give no idea of this. If the vibrating rattle dips 

 into water, a peculiar sound arises which completely resembles 

 the hissing of red-hot iron when it is plunged into water. 

 Beneath the water the rattling is almost noiseless. If a 

 Rattlesnake is held with one hand behind the head, while the 

 other hand grasps the end of the tail just behind the rattle, it 

 becomes impossible for it to make a noise. 



I have attempted to determine the number of vibrations 

 which the rattle makes per minute. A large Rattlesnake was 

 grasped by the neck, while an assistant thrust a needle 

 through the middle joint of its seven-jointed rattle in such a 

 way that it pierced the rattle in its greatest diameter — conse- 

 quently from above downwards, if we imagine the snake 

 lying quiet with its tail outstretched upon the ground. Now, 

 since the rattle (in the position in which we have supposed 

 the snake to be) is, in making a noise, moved from left to 

 right and back again, the needle was able to trace curves of 

 vibration upon paper blackened with soot. As a registering 

 apparatus 1 used Dudgeon's polygraph, with a strip of black- 

 ened paper which was made to slide rapidly forward by means 



