8i4 AGGLUTININS AND THEIR APPLICATIONS 



strated that there are natural or normal agglutinins and hemagglutinins as well as 

 specific agglutinins for bacteria and red blood cells. The former are present in the 

 blood of normal animals; the latter, in that of immunized animals. The origin of 

 normal antibodies is obscure. Certain types of protective antibodies such as diph- 

 theria antitoxin are found in the blood of at least one species of normal animal, 

 namely, the horse. The reason for the occurrence of such normal antibodies (often in 

 considerable concentration) has not as yet been satisfactorily explained. Agglutinins 

 were soon found to be only relatively specific, i.e., an agglutinating serum for species 

 A was also found to agglutinate species B, Usually it is true only in very low dilutions 

 of the immune serum. When certain species of bacteria are used as antigens, agglu- 

 tinins in the greatest concentration appear in the blood of the immunized animals for 

 the particular species employed. These are sometimes described as "major" agglu- 

 tinins. Agglutinins may also be found in the serum for other species and are known 

 as "minor" agglutinins. 



It is postulated that in the bacterial protoplasm there is a hypothetical antigenic 

 element, agglutinogen, which in immune animals is responsible for the presence of 

 agglutinins. Many years ago Smith and Reagh,' employing cultures of the bacillus 

 of hog cholera as antigen, found that with this species one type of agglutinin could be 

 produced for the bacterial cell bodies (somatic agglutinins) and another for the 

 flagella. This subject has been again reviewed recently by Arkwright' who has also 

 brought forward some new evidence bearing upon the question as to whether or not 

 there are two distinct antigens or agglutinable substances present at least in motile 

 bacteria of the typhoid-colon group. The experimental evidence supporting the view 

 that there are also two corresponding distinct agglutinins is set forth. The previous 

 work had adduced macroscopic evidence. Arkwright has brought forward micro- 

 scopic proof of the same thing. His description of the microscopic appearance in 

 flagella and somatic agglutination is as follows: 



With flagella agglutination, the flagella become coherent and hampered in their move- 

 ments; individuals in the clumps are held together by cohering flagella, but the bodies of the 

 bacteria do not lie touching, and, at any rate for some time, they may dance at the end of 

 their tether and occasionally show violent to and fro and up and down movements. On the 

 other hand when somatic agglutinin is in operation the surfaces of the bacteria cohere but 

 the flagella on those surfaces which are not touching the neighboring bacteria are free and 

 move vigorously, thereby bringing about active translation of single bacteria and also of 

 clumps. This movement of clumps is like that seen in a rough motile culture clumped by salt 

 and is a familiar phenomenon in an ordinary broth culture of a rough motile strain. Where 

 much clumping has occurred no free bacteria may be present but nevertheless active motility 

 is easily recognised by the movements of the clumps. 



Shortly after the discovery of bacterial agglutinins it was shown by Malvoz that 

 many substances other than serum were capable of clumping bacterial emulsions in a 

 non-specific fashion. Similarly, it was demonstrated that emulsions of certain species 

 of bacteria if allowed to stand would undergo "spontaneous" or "salt" agglutination. 

 This phenomenon is of course not a specific antibody-antigen reaction. Arkwright, in 

 ■ ' Smith, T., and Reagh, A. L.: /. Med. Research, lo, 89. 1903-4. 

 ^ Arkwright, J. A.: J. Path, b' Bad., 30, 345. 1927. 



