H. W. MARETT TIMS. 



TABLE III. 



COMPARISON OF LIMB MEASUREMENTS OF SPECIMENS IN THE 'BELGICA' AND 

 ' DISCOVERY ' COLLECTIONS. 



The following conclusions arrived at by Professor Leboucq from his four 

 specimens are fully borne out by the study of this additional material, viz. : 



1. The length of the limbs does not remain of constant proportion to that 

 of the body. 



2. The proportion per cent, increases from the earlier to the later stages. 



3. The increase in the hand and foot does not remain parallel, but is in favour 

 of the foot. 



And further the surmise that, in stages younger than those in his possession, the 

 proportions of the two extremities would be equal, is shown to be correct by the 

 younger embryos of the ' Discovery ' collection. 



The limbs appear as buds, with bulbous extremities, which spring out almost at 

 a right angle to the long axis of the trunk (fig. 1) with the flexor surface apposed to 

 the body, the radial and tibial borders directed anteriorly, and the median axes 

 of the arm and leg directly continuous with those of the manus and pes. This 

 continuity of the axis persists from a short time after the appearance of the digits 

 (fig. 4). Very soon, however, the manus becomes ulnar flexed, so that the median axis 

 of the hand forms an obtuse angle with that of the arm, the radial border of the 

 forearm being in a direct line with the radial border of the pollex (fig. 5). Up to this 

 point the change in position seems to have affected the hand only, but now the whole 

 limb begins to assume a backward direction, the axes of the hand and arm once more 

 become almost continuous (figs. 6, 7). In the case of the hind limb the backward 

 extension is gradual but continuous, the movement affecting the whole extremity 

 simultaneously. 



