424 JAMES CRAWFORD WATT 



anlage in the earliest stage of the Hmb skeleton as the distal end 

 of the condensed scleroblastemal core. 



In view of the facts already expounded it seems to me that 

 this latter view is not likely to be correct. The ulnar nerve 

 ought to have a digital cutaneous distribution if the ulnar fingers 

 of the hand are represented in this common finger, but the ulnar 

 does not pass out on the digit, thus supplying one argument 

 against this hypothesis. 



The presence of one digit at the elbow joint on the right arm 

 postulates the separation of one digital rudiment from the com- 

 mon mass. If it separated then clearly the tendency to division 

 of the skeleton of the hand into rays was present and it is just 

 as tenable to suppose that the five-rayed condition of the hand 

 was provided for, but growth suppressed in four, as it is to sup- 

 pose all five rays of one hand and four in the other to be in- 

 cluded in a common mass. 



The fingers here present, both in the hand and at the elbow, 

 as will be seen from the table of measurements, are normal in 

 size for a single digit. The development of an undivided com- 

 mon digital mass might be expected to produce a condition of 

 macrodactyly, which is not found here. Considering all the 

 facts, the view that the digit as found on the hand here repre- 

 sents only one of the five of the normal hand seems to be the 

 correct view in this case. 



What carpals are present is not capable of definite answer. 

 There are only two present, a proximal one articulating with the 

 radius and bearing beyond it a distal one which carries the digit. 

 These two in their shape as previously described resemble the 

 navicular and lesser multangular more than any of the other 

 carpals. Their absolute identification, however, as these two, 

 is hardly to be warranted from these facts alone. If it be true 

 that these are the two carpals present it adds another proof for 

 the digit being the index finger as these two particular carpals 

 are in the direct line of the radius and the second digit. 



In the mechanism of the production of the deformity in the 

 limb several different conditions have to be considered. First, 

 in the early limb bud the ulnar segments may not have been 



