20 PHYSIOLOGY AND TOXICOLOGY 



CHAPTER III. 



THE PHYSIOLOGICAL MECHANISM OF THE BITE OF THE CROTALUS. 



The preceding details will enable us to understand the following statement of 

 the functions of the various parts described, and to appreciate the mode in which 

 thej' combine to effect a given purpose. 



Of the many authors who have treated of the anatomy and physiology of the 

 Rattlesnake and other venomous serpents, no one has entered fully into the subject 

 of the mechanism of the movements which inflict the bite and inject the poison. 

 Redi, Fontana, Tyson, Ranby, Smith, Home, Duvernoy, Soubeiran, and others, 

 have nearly all in turn contributed something to this subject, but I find nowhere a 

 full and complete account of the part played by the various muscles and of the 

 exact uses of many of the peculiar arrangements of tissue which characterize the 

 poison apparatus. Nothing, in feet, can be more admirable than the mode in 

 which the motions in question are effected, and yet while they interest the physio- 

 logist, from the wonderful example they afford of a series of complex acts following 

 one upon another in ordered sequence, to effect a certain end, they are not less 

 interesting to the physician, who may learn from their study how he may be 

 deceived as to the occurrence of poisoned wounds, and how the snake which 

 appears to strike may really fail in its object, even though seeming to have 

 inflicted a wound. 



When the Rattlesnake is in repose and unmolested, it sometimes lies at length, 

 sometimes coiled, or wrapped fold on fold in the loops formed by other snakes which 

 may happen to be in the same box. So soon, however, as cause is seen for alarm, 

 the snake extricates itself, if among others, and at once throws its body into the coil 

 so familiar to any one who has seen serpents, whether venomous or not. Some- 

 times on the edge, more often in the centre of the coil, the tail projects far enough 

 to admit of its vibrating fi-eely, and with singular swiftness. 



The head is raised a little above the rest of the body, but not, usuallj'^, more 

 than three or four inches, even in large snakes. The neck and upper end of the 

 trunk are not thrown into complete circles, but lie in two or three abrupt 

 curves across the mass of the coiled body. The snake is now in position to strike. 

 While thus at bay, in an attitude of singular grace, the long black tongue is fre- 

 quently protruded, a common movement among all serpents when irritated. Just 

 before the blow the snake makes a hissing sound, which is caused by the act of 

 expiration, and is due to the passage of air through the narrow glottis. It is 

 louder in certain innocent serpents than in the Crotalus. 



Tlie mechanism of the forward cast of the body, which next occurs, is a very 



