DR. EVANS ON THE POISONED SPINES OF THE VVEEVER FISH. 365 
The following experiments I carried out with venom 
extracted from recently caught fish. Haemolysis took place 
without the addition of sera with the blood corpuscles of 
Roach and Perch when one drop of venom was added to a 
suspension of their blood corpuscles made according to 
Briot’s technique. 
It seemed important, having made these preliminary 
investigations with the blood of fish, to carry them further 
into the realm of warm-blooded animals, and for this purpose 
I provided myself with an excellent centrifuge worked by 
water power made by Baird and Tatlock. The blood of the 
following was used : — Pigeon, Guinea-pig, Sheep, Dog, Ox, 
Horse and Man. The more exact methods of haemolytic 
experiments as employed by Ehrlich’s School and fully de- 
scribed in an article by Morgenroth in Ehrlich's collected 
studies on immunity, were used in these investigations. 
The blood having been defibrinated, was centrifuged to 
remove the serum, which was carefully pipetted off. io C. C. 
of normal saline was added to .5 C. C. of corpuscles and well 
mixed, centrifuged and the clear solution pipetted off. This 
was repeated three times and finally a 5 ° u emulsion of red 
corpuscles was made in .85 salt solution, either 2 C. C. or 
1 C. C. of this solution was put in a series of tubes, the poison 
added in varying doses and the mixtures put into the incu- 
bator for two or more hours. They were then allowed to 
settle in a cool place for several hours. 
With Pigeon’s blood one drop of a 50 % solution of fresh 
Weever poison was sufficient in two hours to produce marked 
haemolysis. 
The poison solution used was obtained by extracting the 
venom with a needle and syringe previously sterilised ; in 
order to get all the milky fluid from the syringe, an equal 
quantity of salt solution was added to wash it out. so that 
one obtained a 50 ° 0 solution of fresh poison. This was 
kept in a cellar on a block of ice in the dark and in this way 
its virulence remained intact. From a great number of 
experiments I found that uniform results were obtained if 
the poison was removed from freshly caught fish, and extracted 
