254 VENOMS 
did not take place until twenty or thirty minutes later, the toxicity 
of the venom no longer reappeared. 
On the other hand, the admirable researches of Kyes and Sachs, 
and subsequently those of Morgenroth, pursued under the direction 
of Ehrlich at the Laboratory of Experimental Therapy at Frank- 
fort, have proved the readiness of venom to enter into chemical 
combination with certain elements of normal serums, in particular 
with lecithin, a combination which results in the formation of 
hemolysing and non-toxic lecithides, the newrotoxin being left free. 
It therefore seemed impossible to deny the existence of a 
chemical reaction between the venom and the serum, which was 
until quite recently considered as proved. We shall see presently 
that this is not the case. But let us first endeavour to determine 
the laws that govern the neutralisation of variable quantities of 
venom by antivenomous serum. 
If, in a series of test-tubes, we bring the same quantity of cobra- 
venom (e.g., 0°00005 gramme, a dose which is invariably lethal to the 
mouse in two hours) into contact with progressively increasing 
quantities of an antivenomous serum (e.g., 0°01 c.c., 0°02 c.c., &e., up 
to O'l c.c.), and, after thirty minutes of contact, inject these different 
mixtures subcutaneously into a series of mice, we find that all 
those that have received the mixtures containing less than 0°05 c.c. 
of serum succumb after variable intervals, while all the rest survive. 
It is evident that, under these conditions, the serum experi- 
mented upon has shown itself capable of neutralising im vitro, in 
a dose of 0°05 c.c., 5 centimilligrammes of venom. 
The same serum should therefore neutralise 1 milligramme of 
venom in a dose of 1 c.c., that is to say, that this mixture injected 
into a mouse ought to be entirely innocuous. Experiments show, 
however, that in reality it is necessary to mix 1'2 c.c. of serum with 
1 milligramme of venom in order that the inoculated mouse may 
not succumb. 
This proves that, in the initial mixture of 0‘00005 gramme of 
venom + 0°05 c.c. of serum, there remained an exceedingly small 
