of extract for different clinical purposes received no general support. On the other hand, the members familiar with the practice of certain countries were unwilling to accept, as suitable for every country, the strength of extract (namely, that of a 0.5 per-cent extract of the standard powder) which had been adopted by the United States Pharmacopoeia, Edition X, and recommended by Professor Voegtlin to the Conference for general adoption.
After a somewhat lengthy discussion, the President suggested that the Conference might consider the possibility of adopting a method of indicating the strength of the extract, which would secure an international uniformity of notation, and at the same time allow a wide discretion as to the strength of extract to be included in a pharmacopoeia, as suitable for the practice prevailing in a particular country. His suggestion was that the extract might be labelled, like the solution of insulin, in units of activity, and that the Conference might consider the desirability of defining, as one unit of activity for pituitary preparations, the specific activity of 0.5 milligramme of the standard powder. This suggestion met with general approval.
Further questions discussed were the desirability of fixing limits of hydrogen-ion concentration for the extract, and methods of dispensing it, such as would ensure the practical permanence of its activity. Prescription of a hydrogen-ion concentration between the limits represented by pH.4 and pH.5 was considered a satisfactory safeguard, provided that the sterile extract was sealed in ampules of hard glass.
The Conference appointed the President and Professor Voegtlin to act as a Sub-Committee, to embody the various points on which agreement had been reached in the form of resolutions, for final adoption by the Conference. These resolutions, as presented to a subsequent meeting and unanimously adopted by the Conference, were as follows : "The Conference recommends :
"i. That the dry (acetone) extracted substance of the fresh posterior-lobe of the pituitary gland, which was recommended by Professor Voegtlin to the Edinburgh Conference as suitable for adoption as a standard of activity for pituitary extracts, and which has since been adopted as the standard for this purpose in the United States Pharmacopoeia, Edition X, be now definitely accepted as the International Standard.
"2 . That, since the evidence before the Conference indicates that, by strict adhesion to the instructions for its preparation, as given in the United States Pharmacopoeia, Edition X, a sample of this powder of standard strength can be prepared at any time and in . any country, the authority responsible for biological standardisation, in each country concerned, should prepare such quantities of the standard as are needed for distribution in its own country. That Professor Voegtlin be requested to furnish, on behalf of the Health Organisation of the League of Nations, a small sample of the standard, as originally prepared for examination by the Edinburgh Conference, to any authority which may need it for confirmation of its own national standard.
"3 . That it be recommended to the authorities responsible in the different countries for the Pharmacopoeias that a dry preparation of the pituitary posterior lobe, prepared in exact accordance with the method indicated for preparing the standard powder, should be included in each Pharmacopoeia, to serve as the official raw material for the preparation of the official watery extract.
"4. That in order to ensure the stability of the liquid extract prepared from such a powder, the hydrogen in concentration should be adjusted to within the limits represented by P. H. 4 and P. H. 5. The extract should be sterilised and sealed in ampules of non-alkaline resistance glass.
"5 . That the pharmacopceial dried preparation and the extracts prepared there from should be biologically assayed in comparison with the standard, the extracts from the standard powder, and from the pharmacopceial dried preparation, being prepared for biological comparison according to-the method- indicated in the United States Pharmacopoeia, Edition X. For the purpose of the biological assay, the test on the isolated uterus of the virgin guinea-pig, as described in the United States Pharmacopoeia, Edition X, is recommended, as giving the most accurately quantitative results, among the available methods. As additional methods may be recognised the test for pressor activity on the anaesthetised dog or the decapited cat, and the test for anti-diuretic action on the unanaesthetised dog.
"6. That in making the assay by the action on the guinea-pig's uterus, it is recommended that a test for non-specific, stimulant activity on that organ should be applied. This can be done by treating the extract under examination with normal NaOH for one hour at the ordinary temperature (20° C.), neutralising to litmus paper, and re-testing. Not more than 5 per cent of the activity of the uterus should survive this treatment.
"7. That the strength of all pituitary extracts should be expressed in units of activity, the activity corresponding to 0.5 milligramme of the standard powder being defined as one unit, so that the official liquid extract of the United States Phramacopceia, Edition X, would contain 10 International units of activity per c.c.,(while that of another country r. , might be made to contain any larger or smaller number of such units, in accordance / with the prevailing clinical practice of that country/)
Professor Macleod introduced the subject of insulin, on the basis of the memcrandum which he had presented to the Conference, recommending the adoption, as the international standard, of the dried preparation of insulin hydrochloride, which, at the request of the