294 THE ROLE OF AGGLUTINATION IN LMMUNITY, 



and subsequently dissolved.* It is probable that without this 

 coagulation and consequent inception by the phagoc3^tes, the 

 albuminoid could not, on account of its non-diffusibility, be so 

 speedily removed. 



It promised to be an easy matter to put these ideas regarding 

 the function of agglutination and precipitation to the test. If 

 normal bacteria such as Bad. typhi are not engulfed by the 

 mobile phagocytes and agglutinated typhoid bacteria are englobed, 

 then the matter is proved. And since agglutination is but a 

 special case of precipitation, it follows that the function of 

 agglutination is also the function of precipitation. 



The typhoid bacterium is one of the weaker microbes, and is 

 attacked by the immunity bodies of normal blood. These com- 

 prise the bactericidal, the bacterioWtic and the opsonic bodies. 

 The first two of these attack the bacteria in the blood and tissue 

 fluids, and the effect is shown by a loss of staining power and by 

 a swelling, alteration, or disappearance of the bacterial proto- 

 plasm. The opsonic bodies or opsonins also act in the blood, etc., 

 but the effect is made manifest by phagocytosis. The opsonic 

 effect would therefore interfere with the demonstration of what 

 I may call the agglutinative effect, since, if my contention is 

 correct, both effects are demonstrated in the same manner, viz , 

 by phagocytosis. On this account the properties of the opsonins 

 require consideration. 



The opsonins occur in the body-fluids of normal animals in 

 which they were discovered by Wright and Douglas, f They are 

 thermolabile, being destroyed when exposed for ten minutes or 

 longer at 60*. Bulloch and Atkinl; found that they were 



'Since reading that paper to the Society in April, I find that Michaelis 

 published a survey of the work of himself and others upon the precipitins in 

 the second April part of the Biochemisches Centralblatt. He brings forward 

 or accepts this idea as the physiological signification of the precipitins, and 

 compares it to the increase in the phagocytic power of the leucocytes towards 

 streptococci which have been treated with their antibodies, as had been 

 shown by Neufeld and Kimpau(n). I have not been able to see the paper of 

 these authors or an abstract of it, but from Michaelis' reference it appears 

 probable that the antibodies would include the opsonins of Wright and 

 Douglas. 



t Proc. Roy. Soc. Ixxii. (1903), 357, and Ixxiii. (1904), 128. 

 :;: Ibid. Ixxiv. (1904), 504. 



