482 ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 64 



may have the other activities. Until the fractions responsible for the 

 deleterious effects of venoms has been isolated and studied individually, 

 and in combination, one must consider all venoms as substances capable 

 of producing several clianges, sometimes concomitantly, in one or more 

 of the organ systems. 



THE ANIMAL'S SIDE 



Most data on the zootoxicological properties of venoms are based 

 on our studies on mammals, which, of course, makes them of limited 

 usefulness for understanding the design of some of the toxins in the 

 animals' armament. The venom of Latrodectus^ for instance, did not 

 evolve and adapt to the problems existing between that spider and the 

 mammals. Thus, it is not surprising to find that its venom is 20 times 

 less lethal to some insects than it is to the mouse, while on the other 

 hand it is also 10 times more lethal to certain other insects, which have 

 not adapted in the same manner. Some sharks appear to be relatively 

 immune to stingray venom while others from completely different 

 habitats are very sensitive to this toxin. The California moimtam king 

 snake is highly immune to the venom of the Southern Pacific rattle- 

 snake. A dose which would make a man dangerously ill, or may even 

 kill him, has no observable effect on the king snake. The remarkable 

 thing is that this venom, which produces such necrotic lesions in mam- 

 mals, fails to produce even the slightest necrotic wound in the kmg 

 snake. Thus, care must be exercised in applying data derived from 

 studies in one group of animals to conclusions about the biological 

 effects of a venom in another group of animals, or to data on the design, 

 use, and adaptation of the venom (pi. 1, fig. 1). 



Perhaps some considerations for classification might be proposed on 

 the basis of the use to which the animal puts its toxin. Most venom 

 delivered from the head, or more generally from the oral pole, of the 

 animal is used during an offensive act, as in the gaining of food. This 

 is particularly evident in the snakes and only slightly less so in the 

 spiders. The venoms of these animals tend to have a higher enzymatic 

 content than those delivered from the anal end, i.e., from the aboral 

 pole of the abdomen, as those of the scorpions and bees. However, 

 both of these groups use their toxins as part of their offensive arma- 

 ment ; whereas the toxins of most venomous fishes and the poisons of 

 certain amphibians, which are derived from dermal tissues, are used 

 in the defensive armament. These latter toxins contain few or no 

 enzymatic constituents. The snake uses its venom to immobilize 

 or kill its prey, and to aid in its digestion. The prey is incapacitated 

 by the toxin so that it becomes unnecessary for the snake to hold it 

 after envenomation, thereby avoiding the possibility of being bitten. 

 In most instances the venom kills the animal so quickly that it rarely 

 has time to stumble more than a few feet from where it has been struck. 



