One of the most frequent and economically important arrests in development in swine is cryptorchidism. This is a condition in which one or both testicles fail to descend into the normal position in the scrotum. Its frequency of occurrence in hogs is illustrated by reports from federal inspectors-in-charge at various packing centers in the United States which reveal that 10 to 30 cryptorchids are found in each 10,000 head inspected .. This is a significant figure when one considers that the average monthly receipts in Chicago alone are 480,000 hogs.