56 Dr. A. E. Feoktistow on the Physiology of the 



eighteen joints are rare ■^. As a rule, the rattle only lasts 

 lona: enougli to become eio'ht- or nine-jointed. 



Wlien a rattle has fallen ofT, its last-formed joint (con- 

 sequently the first, counting- from the base) at least is always 

 left behind on the tail; for it is firmly united with the latter, 

 until it is replaced by a wqw one forming underneath it. 

 This last-formed joint of the rattle has not the dusky-brown 

 colour of the older joints. It is rather of a horn-like trans- 

 parency, and only of a faintly yellowish tint. Showing most 

 distinctly through the thin walls of this joint of the rattle, we 

 see the horn-producing cone at the end of the tail as a white, 

 flattened, irregularly conical mass, with a deeply indented 

 tip. 



As I have already stated, I was able to follow the repro- 

 duction of the rattles in the case of five of the Rattlesnakes, 

 which had shed these organs. So long as their rattles 

 remained short, the snakes were naturally also unable to 

 make a noise. But the joints were gradually replaced, and 

 in such a way that in all cases in the course of from three to 

 four months two new ones were already present, in addition 

 to the joint already mentioned, which was left behind, and 

 which was now terminal in position. Three-jointed rattles 

 like these produced a fairly loud sound. In the course of a 

 year the rattles developed into chains with from five to six 

 joints, and were then capable of producing the usual very 

 intense rattling sound. The reproduction of the rattles had 

 nothing in common with the ecdyses f. It is well known 

 that the epidermis is shed without the rattle, separating close 

 to the margin of the latter, and, indeed, in such a way that 

 the end of the tail in the cast skin is represented hy an 

 aperture with finely notched edges corresponding to the rows 

 of scales. 



It consequently follows from my observations that a joint 

 of the rattle can be produced in the course of every two to 

 three months \, and 1 do not understand why other observers 

 have not noticed the growth of the rattle in captive Rattle- 



* Rattles of forty-two joints, as figured by Seba, surely exist only in 

 tlie imagination ! 



t Schlegel (' Essai sur la pliysionomie des serpens,' t. ii. 1837, p. 557) 

 thouo-lit that a new joint of the rattle is formed at each ecdysis. This 

 opinion has recently been expressed by Garman also. According to my 

 observations, however, the ecdyses succeed one another much more 

 rapidly (an ecdysis every six weeks) than the formation of the joints of 

 the rattle. 



\ This assertion of course implies the provision of artificial warmth 

 durino- autumn, winter, and spring. In the natural state the growth of 

 tne rattle evidently proceeds much more slowly. 



