The internal secretion of the mammæ as a factor in the onset of labor

The importance of the internal secretions has come to be well recognized in modern physiology and medicine. Among other interesting observations in this field may be mentioned the fact that Miss Lane-Claypon and Starling (Proc. Roy. Soc., 1906, B. 505) have shown that the stimulus to the hypertrophy and lacteal activity of the mammary glands, in pregnant animals, comes not from the ovaries, or the placenta or the uterus, but from the fetus itself. In connection with our studies on the toxic nature of the colostrum of the cow, ill with parturient paresis, we have succeeded in showing that the colostrum both of the normal cow and that of the cow ill with parturient paresis contain a substance, or substances, which have the power to bring on abortion in pregnant guinea pigs; and that neither normal salt solution (0.85 per cent. NaCl) nor the fresh milk of a healthy dairy herd have the power to bring on premature labor. It has also been shown that boiling for a short time does not destroy the power of the normal colostrum of the cow to accomplish premature labor in pregnant guinea pigs.

In this abstract of our paper on this subject we have only space for the details of one experiment, which are as follows:

Experiment 15.—A healthy guinea pig in the 5th to the 7th week of pregnancy received by intraperitoneal injection 10 C.C. of sterile, normal salt solution (0.85 per cent. NaCl). The injection caused no discomfort and at the end of five days she had not aborted. She then received by intraperitoneal injection 10 C.C. of fresh milk, from a healthy dairy herd. This was heated to 38° C. before the injection.