1915] on Anti-Typhoid Inoculation 429 



is being provided with arms with which the invaders may be 

 exterminated. 



4. Lastly comes the essential amboceptor — the immune body, anti- 

 body, sensabilitrice, or fixateur — which represents the bayonet sup- 

 plied on mobilization to the unarmed defender, or complement. 

 (Xumber 7 in diagram d.) 



Amboceptor is not normally present in the body, and a special 

 variety must be formed to deal with each different variety of invading 

 organism. It is a remarkable fact that each is strictly " specific," i.e. 

 will deal only with the particular variety of organism which has led 

 to its production. 



The best illustration of the degree of this specificity is afforded 

 by reference to anaphylaxis. It has been found that if an animal be 

 sensitized by injection of an antigen provided by human blood, that 

 animal will react with a further dose of human blood, but will give 

 no reaction with blood derived from any other animal. It has thus 

 become possible to determine the identity of a blood-stain — a matter 

 of the utmost practical importance in criminal investigations. 



Being unaffected by heat, amboceptor can be obtained separate 

 from complement, which heat destroys. 



Having been formed, and always formed in excess in cases which 

 recover, amboceptor resists excretion, and therefore remains in the 

 l)lood for years — or for life — ready mobilized to repel a fresh in- 

 vasion. Its precise role is to attach the complement to the organism, 

 and thus enable the former to destroy the latter by direct lethal 

 action . 



The term immune-body includes a group of substances, com- 

 prising among others agglutinins, bacteriocidins, bacteriolysins and 

 opsonins. The means by which each of these bodies kills bacteria 

 by acting on some limb of their vital ring is best illustrated diagram- 

 matically, and the method by which one of them is estimated will be 

 described later, as an illustration of delicate accuracy of laboratory 

 technique. 



Popular Simile for the Soldier. 



After a very considerable experience of the duty of persuading 

 men to volunteer for inoculation, it has been found that the surest 

 road to success is to explain as far as possible how the method works, 

 and what it is supposed to do. If they can get hold of a general 

 idea that is all that is necessary, as long as there are one or two 

 points of which they can see the proof for themselves. 



The proofs are simply provided — e.g. one of the most effective 

 is to show a hanging-drop of motile enteric organisms and beside it 

 a hanging-drop agglutinated by immune serum. The former alone 

 is one of the most effective methods of obtaining volunteers. A man 

 comes up with a cheerv smile to peer down the microscope ; as he 



Vol. XXI. (No. 109) 2 r 



