ON THE FRACTIONAL PRECIPITATION OF THE ANTIBODY
          CONTAINING PROTEIN OF ANTI-RINDERPEST SERUM:
                   PART I, PRELIMINARY COMMUNICATION

                                              BY

     J. R. HADDOW, B.Sc., M.R.C.V.S., D.V.S.M., I.V.S.,

          K. C. SEN, D.Sc., AND A. C. ROY, M.Sc.,

     Imperial Institute of Veterinary Research, Muktesar.

          (Received for publication on 1st February 1933.)

                                        INTRODUCTION.

        The nature of the antibodies occurring in the serum of immunised animals has
been the subject of much study in recent years, and numerous experiments have
been carried out to separate the particular fraction of the serum with which anti-
bodies are associated from other serum proteins which appear to be inert in this
respect. Many of these experiments have been undertaken with the object of
isolating a particular antibody and of studying its chemical and physical properties.
A review of this aspect of the subject has been given by Hartley [1931], and al-
though a complete separation of antibodies free from proteins has not been effected
up till now, Frankel and Olitzki [1930] and Frankel [1932] being probably the only
workers claiming to have done so, these fractionation experiments have been
utilised in concentrating an immune serum by discarding other fractions which do
not appear to contain any antibody. The greater part of these experiments has
been done on antitoxic sera, and a number of investigators have shown that the
protective substances or antibodies present in immune sera are associated with the
globulin fraction of the serum, either with the so-called euglobulin, with the
pseudoglobulin, or with both, depending on the antigen and also on the experimental
animal. Thus Seng [1899] demonstrated that diphtheria antitoxin was associated
with the soluble globulin or pseudoglobulin fraction of horse serum, and this obser-
vation of Seng was supported by Pick [1901]. The latter worker, however, showed
that in goats immunised against diphtheria toxin the euglobulin fraction instead
of the pseudoglobulin fraction contained the antitoxin, and that tetanus antitoxin

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