This venom has been studied afresh in my laboratory by Noc, thanks to the acquisition of a small supply kindly forwarded to me by C. J. Martin. Noc proved that it possesses _in vitro_ certain properties of snake-venoms; like the venom of _Lachesis lanceolatus_, it induces coagulation in citrate-, oxalate-, chloridate-, and fluorate-plasmas. Heating at 80° C. destroys this coagulant power. Contrary, however, to what is found in the case of the venoms of _Vipera_ and _Lachesis_, the secretion of _Ornithorhynchus_ is devoid of hæmolytic and proteolytic properties. Lastly, its toxicity is very slight, at least five thousand times less than that of the venoms of Australian snakes. A mouse is not even killed by 5 centigrammes of dry extract, and in the case of the guinea-pig 10 centigrammes only produce a slight painful œdema. It has been remarked that the volume and structure of the poison-gland exhibit variations according to the season of the year at which it is observed. It is therefore possible that these variations also affect the toxicity of the secretion (Spicer).[167] By certain authors the poison of _Ornithorhynchus_ is considered to be a defensive secretion of the males, which becomes especially active in the breeding season, and this hypothesis is plausible. In any case it would seem that as a venom the secretion is but very slightly nocuous. It will have been seen from the papers quoted above that the chemical nature and physiology of the various venoms, other than those of snakes, are as yet little understood and need further investigation. The main outlines of this vast subject have scarcely been traced, and the study offers a field of interesting investigations, in which the workers of the future will be able to reap an ample harvest of discoveries, pregnant with results for biological science. PART V. DOCUMENTS. I.--A FEW NOTES AND OBSERVATIONS RELATING TO BITES OF POISONOUS SNAKES TREATED BY ANTIVENOMOUS SERUM THERAPEUTICS. A.--Naja tripudians (India and Indo-China). I.--Case published by A. Beveridge, M.B., C.M., Surgeon S. Coorg Medical Fund (_British Medical Journal_, December 23, 1899, p. 1732). “A strong coolie, aged 26, was bitten by a cobra on the right ankle, just above the internal malleolus. He was brought to the surgery about one hour after being bitten, in a state of comatose collapse. The pulse was rapid, and the surface of the body cold. He was given an injection of 10 c.c. of Calmette’s antivenene deeply into the right flank. He was kept under observation: the paresis and insensibility were very marked. On visiting him some hours afterwards I found he could walk without assistance, but staggered, and complained of weakness and pains in both legs. Next morning he was much improved, the paresis gradually wore off, and the pulse steadily gained strength. The patient returned to work four days later, quite recovered.