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make great advances. Owing to expense, however, the method is not likely to come into general use, nor is it necessary that it should do so, as it is only suitable for cases of definite ailment and not for normally healthy women.

The general principle of all these dome-shaped pessaries, such as the occlusive pessaries and the varieties of the continental small "Mensinga," is the prevention of the spermatozoa from entering the internal os. This is achieved by the use of a small cap to fit over the cervical neck, thus putting a barrier between the spermatozoa and the egg-cell with the least possible interference or intervention of surfaces between the penis and vagina. The use of the small occlusive cap over the cervix leaves not only the greater part of the vaginal canal, but all the end of the vaginal canal round the cervical region in complete and natural contact with the male organ and with the seminal fluids. It interposes merely the barrier of thin rubber between the wandering spermatozoa and the entrance of the cervical canal. How necessary this is in many cases is shown by the occasional failure