PHYSICAL CHARACTERISTICS OF VENOM. 7 



in pairs, or in zoogloea masses. They are less refracting, and paler than the 

 albuminoid particles described above, and respond promptly to the usual tests for 

 bacteria, viz: They multiply rapidly and absorb well the aniline dyes, thus form- 

 ing a marked contrast side by side with the animal granular material, which was 

 readily discolored under the influence of acid. 



The epithelial cells seen in the venom are, as a rule, few in number, are squam- 

 ous or club-shaped, and in size not exceeding that of the red blood-corpuscle of 

 the serpent. Leucocytes are also few in number, and, as well as the epithelium, are 

 mostly covered with micrococci. A few of the white blood-corpuscles do not appear 

 to contain micrococci, and in fresh venom, especially upon the warming stage, 

 exhibit a quite active amoeboid motion. The venom of the moccasin presents the 

 same appearances. 



If fresh venom stands but a short time exposed to the air the micrococci mul- 

 tiply with remarkable rapidity, forming large, pale, motionless clouds ; but, in 

 addition, multitudes of movable bacteria (the Bacterium termo and a bacillus — 

 probably Bacillus subtilis) gradually make their appearance. 1 



The globulous masses, above described, may be collected by filtration, but as 

 this is often a difficult or even an impossible process with a fluid as viscous as pure 

 venom, and, as much is lost in the filter, another method was devised, and there- 

 after frequently used by us as an assistance in venom analysis. A tube, about 5 

 millimetres wide and 200 to 400 m. m. long, has a bulb blown on it midway, or at 

 the top, and is then closed above in the blowpipe flame, and strongly heated 

 throughout. While hot, the lower end drawn to a point, is in like manner sealed. 

 After being cooled the tip is broken within fresh venom, which is forced up into 

 the tube by atmospheric pressure. The end of the tube is then once more adroitly 

 sealed in the flame. 



Thus prepared the tube is suspended, so that the solids of all forms settle in a 

 few days, while for this time, at least, the venom undergoes no such putrefactive 

 change as is inevitable when it is exposed to the air at our ordinary spring or 

 summer temperatures. 



The solids, thus collected below, are easily separable from the supernatant venom 

 by breaking off the two ends of the tube and allowing the precipitate to escape, 

 with a minimum amount of liquid, from which washing in water easily separates 

 them. 



The physical appearances of the venoms of the moccasin or of the rattlesnake, 

 thus secluded from the air in these partial vacuum tubes, undergo some curious 

 changes of much interest. 



The yellow coloring matter disappears from below upwards, and at last is seen 

 only at the top, where the venom is in contact with the small amount of air left in 

 the tube. At first, this change was presumed to be simply the rising of a pigment 

 of lesser gravity. But it was noticed that the layer of yellow was of no deeper 

 tint in its lessened bulk than when diffused. The fluid below it was left as 



1 Fresh venom, putrefied from long standing, appears to lose at least a portion of its virulence. 

 But this is a point which is open to further observation. 



