92 PHYSIOLOGY AND TOXICOLOGY 



Dr. Burnett' states that direct union of venom and blood causes the disks to 

 lose their tendency to arrange themselves in rows. This observation, also, I am 

 unable to verify entirely. Where the blood and venom were mixed in equal quan- 

 tities, the nummulation of the disks was very often prevented, but the poison is so 

 glutinous and gum-like that its mechanical properties may be very well supposed 

 to exert some effect on this process, and certainly, so far as I have seen, the presence 

 of venom to the amount of a tenth or twentieth in no way retarded, much less 

 stopped, the union of the globules of freshly-drawn blood. 



One other observation was yet to be made to complete the study of the influence 

 of venom upon the various parts of the blood. It was clear that in slow venom 

 poisoning the blood plasma became profoundly altered. As it was possible that the 

 contents of the blood-disks might also undergo a like degradation without of neces- 

 sity involving changes in the form of these elements, I examined the blood of 

 several guinea-pigs to determine whether, after death from Crotalus bite, the blood 

 would still crystallize. In some of these cases the blood was very feebly clotted, in 

 one only was it perfectly fluid. In all of these, specimens of blood from the heart 

 afforded me, after the usual preparation, beautiful crystals, nor did these differ in 

 form, size, or color, from the characteristic tetrahedrons of the blood of this animal. 

 In order to complete my study of the blood, I desired to ascertain the rate at 

 which the fibrin disappeared from the vital fluid. 



Experiment. — The first observation on this point was made upon a small dog, 

 weighing about ten pounds. A tube was placed in the left carotid artery, that 

 blood might be drawn from time to time. The various portions of blood were 

 received in glasses of like shape, which were labelled and set aside. 



At 4.15 minutes P. M., a drachm of blood was drawn from the artery; it coagu- 

 lated perfectly well in three or four minutes. 



At 4.20, at 4.24, and 4.26, the dog was bitten by separate snakes, which had 

 been frequently used within four days. From the second wound ran a little blood, 

 which collected in the hollow of the groin, and coagulated feebly. 



At 4.37 about half an ounce of blood was drawn. At 4.36 the dog fell. 

 At 4.46 I removed about two drachms of blood. Like that removed at 4.37, it 

 clotted perfectly. 



At 4.55 respiration ceased, just as a fourth specimen was taken, and at 4.58 all 

 motion was over. The specimen last collected coagulated rather freely. 



The wound in the flank was at once laid open, and about two drachms of fluid 

 blood collected from the tissues, which were soaked down to the bones. The heart 

 blood, being drawn into a seventh glass, was still found to be coagulable, but the 

 clot which formed was by no means so perfect as in the blood first drawn. 



At the close of twenty-four hours, the temperature being about 78° F., the speci- 

 mens one, two, and three were unaltered, and had no unpleasant odor; number four 

 was slightly altered, but -the blood from the heart was already unpleasant in smell, 

 and that from the wound was quite putrid. At the end of a second period of 

 twenty-four hours, these changes were much more marked. 



Burnett, op. cit. 



