It is formed about the third month _outside_ the membranes covering the child and is more or less loosely attached to the uterine wall. The umbilical cord is attached to its fœtal surface, inside the ovum. Like a flat sponge it takes oxygen, blood, and the nourishing fluids from the blood vessels in the uterine wall, carries them to the child by means of the umbilical vein, and carries back the carbonized blood and waste products by the umbilical arteries to the placenta, and there returns them to the maternal blood for disposal. The blood of the veins is bright red, and of the arteries, dark and turbid. [Illustration: Fig. 20.—Normal attitude of fœtus (complete flexion). (Barbour.)] There is no direct communication between the maternal tissues and the placenta, hence all the changes occur by osmosis, and by the activity of the cells which form the walls of the villi. =The liver= of the child is large and active. The stomach and intestines functionate mildly. The kidneys act, and urine is discharged into the liquor amnii, which the child occasionally swallows. During development, the movements of the child become more and more pronounced. Arms, legs, and entire body participate in turn. Periods of rest are also observed. Gradually the child assumes a definite attitude in the uterus. It becomes more and more folded and flexed to accommodate its size to the limitations of space. The head bends on the chest, the arms are folded, the thighs flex against the abdomen, the legs on the thighs, and even the back ultimately becomes convex. It attains a complete flexion, the normal attitude of the child. As maturity approaches, the head becomes more and more palpable and seeks its usual location in the lower pole of the uterus, resting on the pelvic brim. [Illustration: Fig. 21.—Fœtal skulls showing sutures. Note the differences between the anterior and posterior fontanelles. (Eden.)] [Illustration: Fig. 22 _A_.—Child’s head at term (from side), showing diameter. (American Text Book.)] [Illustration: Fig. 22 _B_.—The child’s head at term (from above), showing diameters and fontanelles. (American Text Book.)] =The fœtal skull= at maturity (at term) is still incompletely ossified. The bones are thin and pliable and separated at their edges by intervals of unossified membrane which form the sutures and fontanelles. Thus the skull is compressible to a slight degree and capable of much change in shape. It can be measurably moulded by the uterine contractions to suit the pelvis. In front, the two coronary sutures meet the frontal and sagittal sutures to produce a kite-shaped figure, called the large or anterior fontanelle, or the bregma. Behind, the lambdoidal suture meets the sagittal suture to form the small or posterior fontanelle.