1. On the evidence of this series of cases I would suggest that the congenital defects of long bones have no connection at all with outside pressure, but are due solely to interference with growth in the limb buds during the first few weeks of foetal life.

2. Deformities associated with defects of the fibula are usually not so severe as in the case of femur or tibia and it is generally possible to effect improvement by operative and mechanical means.

3. Deformities associated with absence or defect of the tibia are generally very severe, and usually amputation alone is possible.

4. Associated with absence of the tibia are many serious alterations in the muscles, but chiefly such as would be expected under such conditions.

There is, however, a strong tendency to persistence and often hypertrophy of a muscle which arises from the fibula and inserts into the same bone. This may be the vestigial tibio-fibular muscle or it may be a very abnormal tibialis posticus. The latter possibility is strengthened by the absence of the tendon of that muscle in the sole.

5. Defects of the femur are usually associated with a normal, or nearly normal, lower segment, and in these cases operation devised to equalize the length of the two femora is well worth consideration.