ZOOLOGY. 349 



fied by the shock. The mortification is not confined to the muscles, 

 the cellular tissues, and the vessels ; in the sphacelated veins the blood 

 coagulates and then, soon sharing the general decomposition, the clots 

 putrify and engender putrid gasses, which soon break the weak lien of 

 the clot, penetrate to the liquid blood, mix themselves with it, are car- 

 ried along in its circulatory movement, and carry death into every part 

 of the body. The Doctor saw this in May, 1861, for the first time : 

 while making profound scarifications to combat emphyseme, numerous 

 bubbles of gas issued from the orifice of the veins ; the bistouri divided ; 

 the subject died that night ; the autopsy, made twenty-eight hours 

 after death, showed that the gangrened centre was the point from 

 whence these gases came, and that they freely circulated in the veins. 

 He has successfully combated it by amputation. 



NOTES ON THE RATTLESNAKE. 



The following communication was presented to the Boston Society 

 of Natural History, by Dr. W. I. Burnett. Among a number of living 

 reptiles placed at my disposal by Dr. Dearing of Augusta, Ga., for 

 anatomical and physiological uses, were two quite large and beautiful 

 Rattle Snakes {Crotalis durissimusj, with which I lost no time in 

 making many experiments. The largest, a little more than four feet in 

 length, and having fourteen rattles,* was killed, and I made a dissec- 

 tion of its mouth in order to learn some details of the anatomical 

 relations of the fangs and poison-apparatus. As the opportunity for 

 the study of the progressive development of these was an unusually 

 good one, I will give the results somewhat in detail. 



The two fangs in use with the poison-sacs at their base, presented 

 nothing remarkable, excepting that they were old and worn, and evi- 

 dently soon to be shed. But directly behind these, the mucous 

 nembrane on each side was crowded with what may be called the 

 fangs of reserve ; for like successive teeth elsewhere, they are ready 

 for complete development in turn, as fast as those in use passed away. 



These were of all sizes from near that of the fangs in use, down to 

 the smallest germ, and I was able to easily count twelve on each side. 

 Their development, studied with the microscope, appeared as fol- 

 lows : First, a minute involution of the mucous membrane (the 

 tooth-follicle.^) In this is seen a small conical papilla as the first trace 

 of the future fang. This is gradually developed by the aggregation of 

 cells, and when about 1-25 of an inch in length its cavity (the pulp- 

 cavity} is occupied with a network of blood-vessels. The growth after 

 this is more rapid and determinate. The epithelial cells covering the 

 apex of the papilla become lineally arranged, and fusing together, form 

 fibers, which, when filled with calcareous salts, constitute the intimate 



The popular belief is that the number of rattles on the tail indicates the years of 

 the snake's life. But according to several observers (Buchanan, Holbrook and 

 Deariug) this is not so; for not only may it loose several of the rattles by acbident, 

 but two and even four have been known to form in a single year. One of my own 

 accidentally lost two of its rattles, and it is rare to find specimens having more than 

 ten or twelve. 



