354 IMMUNITY AND CURATIVE INOCULATIONS 



adhere to one another as an inactive " clot " or " lump "). 

 As the " agglutinating " poison is peculiar (or nearly 

 so) for each kind of microbe, we can tell whether a 

 patient has typhoid by drawing a drop of his blood into a 

 tube, and adding some fresh living typhoid bacilli to it. 

 If the patient has typhoid he will have begun to form the 

 " typhoid-agglutinating " or " typhoid-paralysing " poison 

 in his blood, and the experiment will result in the " aggluti- 

 nation " (sticking together in a lump) of the typhoid 

 bacilli. And so we prove, in a doubtful case, that the 

 patient has typhoid. 



The third chemical activity of the blood in dealing with 

 poisonous microbes is also one which is conferred upon it 

 by its living cells when excited by the presence of those 

 microbes. It is the production of a " relish " (for so it 

 must be called) which attaches itself to the microbes and 

 renders them attractive to the eater-cells (the phagocytes), 

 so that those swarming amceba-like floating particles at 

 once proceed to engulf the microbes with avidity. In the 

 absence of the relish (the Greek word for it used by Sir 

 Almroth Wright, its discoverer, is " opsonin "), the eater- 

 cells are sluggish too sluggish in their work. They 

 resemble a child who will not eat dry toast, or, at best, 

 only slowly, but will devour rapidly many pieces when the 

 toast is buttered. It is of the utmost importance to us 

 that our white corpuscles, or eater-cells, should not be 

 sluggish but greedy. 



There are some microbes which will produce deadly 

 poison if grown in the clear fluid (serum) of the blood of an 

 animal (as, for instance, the cholera-microbe when grown in 

 the serum of the frog's blood), yet when inoculated living 

 into the blood of that animal never cause the slightest 

 illness ? Why ? Because they are at once eaten by the 

 vigilant phagocytes of the blood before they can produce 

 any appreciable amount of poison. That is easily demon- 



