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 rely, in these investigations, upon one particular boiled organ. The great advantage of the whole method of investigation is the fact, that it is possible to make each case absolutely sure by means of control experiments. Placenta, for instance, can always be tested by means of serum from definitely non-pregnant individuals, as well as from males. Further, all kinds of organs should be subjected in turn to the action of a particular serum.

The sero-diagnosis of pregnancy has been recently employed with success by numerous scientists. While many observers agree with our point of view, that the defensive ferments which appear during pregnancy are directed against the albumen of placenta, other authors are of the opinion that no strictly specific action exists. But surely positive facts have more value than negative ones.

We are so strongly persuaded, from our own experiences, of the certainty of our methods, that we do not hesitate to demand that no one should deal with pathological cases by means of the dialysation method and the optical method, who has not given evidence of having been able to produce 100 per cent. of correct diagnoses from pregnant, and particularly from non-pregnant, individuals, using placenta as his substrate. Should the technique of the student be