2/2 PHYSIOLOGICAL CHEMISTRY. 



the suspected typhoid fever patient is mixed on a slide with a 

 bouillon culture of typhoid bacilli. After a time the mixture 

 is examined with the microscope. If the suspected blood con- 

 tains the agglutinins developed in the disease " clumping " or 

 precipitation of the bacteria from the culture must follow. (It 

 is held as characteristic that loss of motility must also be ob- 

 served.) The intensity of the agglutinin reaction may be 

 estimated by noting the degree of dilution in which the blood 

 serum will still agglutinate the bacteria from the bouillon 

 culture. 



Other Anti Bodies. In the above brief survey of the sub- 

 ject of anti bodies present or developed in the blood only those 

 which have been the object of most frequent investigations 

 have been mentioned. Bacteriologists have called attention 

 to numerous other varieties or subdivisions, but it is not the 

 purpose of this chapter to take up the discussion of details. 

 What has been given is sufficient to call attention to the 

 broader principles concerned. 



CHEMICAL NATURE OF THE ANTI BODIES. 



On this topic much has been written, but as yet no satisfac- 

 tory answer can be given to the question : What are they chem- 

 ically? As formed in the serum of blood or in milk it may 

 reasonably be assumed that they must bear some relation in 

 composition to the protein bodies. On this basis attempts have 

 been made to separate them by fractional precipitation reac- 

 tions such as were developed by Hofmeister and others for the 

 proteins and which have been detailed in former chapters. 



It appears from the evidence thus far offered that some of 

 these bodies, at least, must be classed among the globulins. 

 Pick and others have recently been able to separate the active 

 substances from several kinds of immune sera and establish 

 pretty accurately the limits of precipitation. The active frac- 

 tions separated contained the real anti bodies in minute amount 

 only, probably. In some cases they were found in the euglob- 

 ulin fraction, and in other cases in the pseudoglobulin fraction 

 of the precipitate. 



