ABSTRACTS                              175

      3.  Successful transmission has been effected by as few as four infecting bites.

      4.  Direct transmissions of T. brucei by the agency of G. tachinoides have only proved success-
ful where the average number of trypanosomes in the peripheral blood of the infected animal exceeds
one in five microscopic fields.

      5.  Some difference appears to exist in the direct transmissibility of the three strains of T. brucei
used.

      6. Negative results have been obtained in each of fifteen direct transmission experiments in
which attempts were made to transmit six strains of T. gambiense by the agency of G. tachinoides.

      7.  T. brucei has been successfully transmitted by S. calcitrans by the direct method.

      8.  Experiments in which attempts have been made to employ A. costalis, A. funestus, Aëdes
vitatus, and Lyperosia (sp?) as mechanical vectors of T. brucei have failed to effect transmissions.

      9.  Dissection and examination of the proboscis of G. tachinoides at intervals after an infecting
meal, reveals the fact that motile trypanosomes may survive in the proboscis for as long as three
hours ; and that the maximum number of trypanosomes contained in the proboscis immediately after
an infecting meal is often very considerably in excess of 600 when trypanosomes are abundant in
the peripheral blood of the infected animal.

      10.  A brief account is given of the behaviour of trypanosomes taken up during an infected
blood meal in the proboscis and gut of Stomoxys, A. costalis, A. funestus and Lyperosia. In none
of these flies do the trypanosomes survive in the proboscis as long, or in such large number, as in
G. tachinoides.

      The Nature of Milk Fever.—Professor J. RUSSELL GREIG, Ph.D., M.R.C.V.S.,
Director, Animal Diseases Research Institute, Moredun, Edinburgh. (Eleventh Interna-
tional Veterinary Congress, London, 1930.)

                                                SUMMARY.

      (i) There is no difference between the calcium values in parturient cows and those in non-
parturient cows and in bullocks.

      (ii) The onset of milk secretion is accompanied by a transient but appreciable fall in the blood-
calcium which returns to normal after the crisis of initiation of lactation is passed.

      (iii) In milk fever there is invariably a pronounced fall in the blood-calcium (82 cases
examined). The degree of severity of the symptoms bears a distinct relation to the calcium level in
the blood. From a series of observations made in one case, before and during the attack, the fall in
calcium appears to be abrupt; it is coincident with the onset and corresponds with the progressive
severity of the symptoms.

      (iv) In an examination of 81 cases of diseased conditions in cattle other than milk fever, none
was found to present a hypocalcaemia in any way comparable to that which obtains in that disease.

      (v) Inflation of the mammae of normal lactating ewes causes a rise in the blood-calcium (about
10 per cent.).

      (vi) Inflation of the mammae of the cow in cases of milk fever results in a pronounced rise
in the blood-calcium. The rise is at first rapid, and the case usually shows definite signs of recovery
when a level of about 6 to 7 mgm. of calcium per cent. has been reached.

      (vii) Injection of calcium gluconate (Sandoz) exclusive of other treatment, elicits specific
curative response in milk fever.

      (viii) The subcutaneous injection of calcium gluconate can abort the milk fever attack.
Evidence is submitted that calcium injection immediately after calving and preferably reinforced by
a second injection about 24 hours later would prove a preventive treatment.