346 EFFECTS OF SNAKE N'EXOMS ().\ DOMESTIC AXO.IALS. 



Rigor is delayed; serious infiltration of the lesion may be 

 present with a few haemorrhages into the substance. The fluid 

 in the serous cavities mav be blood-tinged in the case of N. flofo. 

 T.ungs mav shov,- sub-pleural haemorrhages. 



(2) I'il'crinc J^cnom. — The action of venom of the llpcra 

 nisscUii mav he taken as a good exam])le of this ty])e of venom. 

 The exjieriments by Wall in the dog with this venom show that 

 death occurs very rapidly in five minutes, and post-iuortein 

 examination shovvs some intravascular clotting, especially 

 marked in the portal vein. In smaller animals bitten liy this 

 snake, the intravascular clotting of the blood is very well marked. 

 Hoemorrhages will be found into the area of the bite, and also 

 in the kidney and into the intestine. 



In cases where the dose injected is insufficient to kill 

 rapidly, local symptoms appear, these being more or less exten- 

 sive subcutaneous haemorrhages and an area of ]:)rofuse redema. 

 The extravasated blood may be alxsorbefl and resolution occur 

 without com])lications. or the ]ian may slough or an abscess 

 form, or spreading gangrene ma\ follow. (ieneral sym])toms 

 may develop, of which the following arc the most un])orrant : — 



Ra])id emaciation, profound anaemia and lethargy. ha;nu:- 

 turia. and occasionallv internu'ttent discharge of blood-stained 

 f;eces. There is a fall in lilood i)ressure due to vaso-dilation in 

 the portal systeiu. Init no ])ron()unced alterations in the peripheral 

 circulation are seen. In chronic cases, Laml) and Hanna have 

 pointed out a decrease in the coagulaliility of the blood. Cessa- 

 tion of resi)iration in fatal cases is due to failure of the circula- 

 tion, but there is no direct effect on the respiratory centre, and 

 the phrenics are not paralysed. The heart-beats are continued 

 some time after the respirations have ceased, l)Ut their frequency 

 and volume is very nuich diminished. 



It will therefore l)e seen that \'ii)erine venoms contain toxins 

 which ( 1 } particularly affect the blood and vascular systems, 

 (2) cause sudden onset of sym])toms. and (3) liability to ex- 

 tensive gangrenous destruction of the local lesion if the animal's 

 life is prolonged beyond the acute stage. 



The effects of Vi])erine venom on animals have been 

 recorded Ijy yXndrews, who utilised the venom obtained from two 

 species, Bitis aricfans (puff-adder) and Caiisits rhouibcatus 

 (night-adder). His results may i)e sunimarised as follows: — 



A local lesion was invariably develo])ed, varying from an 

 infiltration, only apparent on posi tnortcm. to an enormous 

 swelling. Its onset was rapid, and was in all cases appreciable 

 one hoiu" after the bite was inflicted, from which time onward 

 it rapidly increased in size and tended to gravitate to dependent 

 l)arts. The lesion was hot and i)ainful to the touch, and resolu- 

 tion was slow. A discharge of fluid through the skin and slough- 

 ing was noted in one animal l)itten b\- tlie puft'-adder, and then 

 only on being bitten a second time after recovery. 



Sym])toms of pain were i:)ronounce(l in all cases, \\ith the 



