TRACHINUS DRACO 



237 



may suppurate or even turn to gangrene. The symptoms may 

 last from two to three hours to several days. 



The venom has been studied by Giinther, Gressin, Bottard, Briot, 

 and Phisalix. It has also been studied by Evans, who, after 

 washing the fish, collected it by means of an aseptic hypodermic 

 syringe, then dried it in vacuo, reduced it to a fine powder, and 

 finally dissolved it in normal saline or in water. He collected 

 the poison from about 2,000 fish. The venom is clear, trans- 

 parent, and very slightly acid. Hypodermically injected, it 

 causes mortification and local paresis, necrosis, and hemorrhage. 

 Intravenously injected, it causes failure of the heart and respira- 

 tory paralysis, associated with first a rise in the blood-pressure, 

 which is followed later by a marked fall. It also appears to have 

 a hsemolytic effect, which is supposed to be due to its amboceptors 

 uniting with endocomplements (lecithin) in the red cell. It will 

 thus be seen that the poison in some respects resembles snake- 

 venom. The venom is lethal to fish, frogs, and mammals. Thus, 

 0-015 gramme of dried venom killed a frog, and 0-02 gramme a 

 mouse. 



Fig. 28. — Trachinus draco Linnaeus. 



According to Briot, who has succeeded in immunizing rabbits, 

 the venom contains a ferment capable of digesting proteid. 



Trachinus radiatus.—Pohl has studied the poison of this fish, 

 and finds that it stops the heart in diastole. The effect of applying 

 the poison to the heart of the frog is to first produce strong con- 

 tractions, which gradually become weaker and weaker, until they 

 cease and the heart stands still in diastole. The poison has, how- 

 ever, no effect on skeletal muscle. 



CoUus. — ^The genus CotUts, widespread in the Northern Hemi- 

 sphere, possesses a poison apparatus which resembles that of the 

 genus Trachinus, but is less developed, and consists of poison 

 glands lying in culs-de-sac in the opercular spines. The cells of the 

 gland only secrete the venom during the spawning season, from 

 November to the end of January. 



Callionymus.- — -In Callionymus the operculum terminates in three 

 conical spines like a trident, and in addition possesses another spine 

 directed upwards, and these are supplied in the spawning season 

 with a small quantity of venom from the gill membrane, which, 

 according to Bottard, has little effect on man. 



