298 MEDICAL JURISPRUDENCE vaginam or externally through the abdominal wall. Ballottement can be tried from the fourth to the seventh month, but the test fails if the amniotic fluid is scanty. In practised hands it is a sign of great value. 12. X-Ray Examination, — This is useful in the diagnosis of pregnancy after the sixteenth week when the centres of ossification have become well developed. The X-ray examination is not harmful to mother or foetus, as the exposure with the modern apparatus lasts only a few seconds. The X-rays are of great assistance particularly in a case of twins where one ovum is suspected to be bigger than the other and in cases of suspected hydatidiform rnole, pregnancy with fibroids, and foetal malformations. 13. The Biological Test. — From the above mentioned signs it is evident that before the sixteenth or eighteenth week there are no certain signs from which a medical man can give a definite opinion about the existence or otherwise of pregnancy. In such a case it is always a safe plan to wait till the definite signs develop or to perform a biological test devised by Aschheim and Zondek in 1928 for detecting pregnancy in its early stage. This test is popularly known as the Aschheim-Zondek test, and is based on the fact that in a pregnant woman an abnormal amount of the anterior- pituitary-like hormone of the chorionic villi is excreted in the urine, and that shortly after the puerperium this excessive excretion of the anterior- pituitary-like hormone stops. The presence of this hormone can be demonstrated by significant developmental changes in the sex organs of sexually immature female white mice, when small amounts of a pregnant woman's urine are injected subcutaneously. The ovaries are enlarged. The corpora lutea are formed and hsemorrhagic spots occur into the follicles. There are often swelling and hyperaemia of the uterus. The technique for performing the test is as follows : — Five sexually immature female white mice, three to four weeks old, and weighing from six to eight grammes, are inoculated twice daily for three days with the catheterized morning urine of the suspected case of pregnancy in quantities of 0.2 cc, 0.25 cc., 0.3 cc., 0.3 cc., 0.4 cc., and 0.4 cc., respectively. One hundred hours after the commencement of the test the mice are killed and the ovaries are inspected with a hand lens or with the naked eye. A positive reaction is characterized by the presence of corpora lutea and haemorrhages into the follicles of the enlarged ovaries. If the urine is turbid, it should be filtered and its reaction made slightly acid if it is not already so. One drop of trier esol to each 30 cc. of urine should be added if the specimen is not to be used at once or if it has to be sent by post.8 The Aschheim-Zondek test gives a positive reaction in 98 to 100 per cent of the cases of pregnancy. It is positive as early as ten to fourteen days after conception and two days after the first missed menstrual period. It remains positive throughout pregnancy and for a period of about seven days after the termination of pregnancy or after the death of the foetus. It also gives a positive reaction in ectopic gestation, hydatidiform mole, chorion- epifhelioma, and certain cases of malignant diseases. • The Friedman modification of this test can be carried out by injecting 7* to 10 cc. of the suspected morning urine into the marginal ear vein of a virgin female rabbit, 12 to 14 weeks old, and weighing not less than 4 pounds. Twenty-four to thirty hours later a positive reaction will be indicated by the presence of corpora lutea and corpora Laemorrhagica in the hypertrophied ovaries of the raHbit There wil abo be marked injection of the tttertte and ovfefecf. IwL $n. Jfei Res^ .July 1031, p. 230.