VENOMOUS ANIMALS AND THEIR TOXINS — RUSSELL 481 



histamine and histamine releasers; and (4) several proteins whose 

 composition has not yet been determined, although there is a likelihood 

 of one or several of these toxic proteins being peptides. 



Studies on the chemistry of fish venoms have been limited by several 

 factors. In many fishes there is no true venom gland ; rather the venom 

 is produced in certain highly specialized secretory cells Avhich lie in 

 dermal tissues that are not otherwise toxic. These cells are shown in 

 figure 1. Unlike the snake venoms, which retain their zootoxicological 

 properties even after 20 or 30 years, the fish venoms are extremely 

 unstable, most of them losing their biological activity on standing for 

 an hour at room temperature. In general, fish venoms are composed 

 of 3 to 10 proteins and have little or no enzymatic activity. They are 

 very unstable when heated and most of the toxic fraction is nondia- 

 lyzable. On electrophoresis one to five fractions can be identified, 

 only one or two of which appear to have biological activities that are 

 deleterious.^ 



The venoms of some species of ants contain formic acid — which is 

 very simple chemically — while others contain a toxin so complex by 

 contrast, as "dendrolasin" C15H22O, fi (4 :8-dimethylnona-3, 7-dienyl) 

 fur an. Bee and wasp venoms are very complex mixtures containing a 

 protein hydrochloride called "mellitin" and a number of other sub- 

 stances including at least seven enzymes as well as 5-liydroxytrypta- 

 mine, kinin, and histamine. The venom of Latrodectus contains at 

 least 12 amino acids. As most spider venoms, it is rich in glutamic acid 

 and A-aminobutyric acid. Six protein fractions have been separated 

 by paper and column electrophoresis, and most of the toxic activity is 

 found in one of them. The venom has spreading activity but no 

 haemolytic activity and does not appear to inactivate cholinesterase. 

 The LD50 for Latrodectus mactans venom is 0.550 mg./kg. test animal 

 body weight. 



The effects of venoms on the various organ systems of mammals 

 and certain arthropods are quite well known. In spite of this, however, 

 and at the present stage of our knowledge, it seems wise to avoid the 

 arbitrary division of venoms into such groups as "neurotoxins, haemo- 

 toxins, cardiotoxins," etc., for while these classifications do serve some 

 useful purpose, they have led to much misunderstanding and certainly 

 to a number of errors in clinical judgment. It has become increasingly 

 apparent from chemical and physiopharmacological studies that these 

 divisions are oversimplified and misleading. Neurotoxins can, and 

 often do, have cardiotoxic or haemotoxic activity, or both ; cardiotoxins 

 may have neurotoxic or haemotoxic activity, or both, and haemotoxins 



2 D. B. Carlisle has demonstrated that some 60 percent of the dry weight of the venom 

 of the weeverflsh appears to consist of toxic mucosubstances, which can be separated 

 into two albumins and an amino polysaccharide, although in the crude venom they are 

 probably associated In a single complex mucosubstance. He has suggested that the 5- 

 hydroxytryptamine contributes to the pain-producing property of the venom. 



