40 THE MENDEL JOURNAL 



Mr. Farabee says that the middle bone is absent, 

 but this does not appear to be the case in my family, 

 for though there are only two separate bones in the 

 adult, the middle one, as will be shown presently, is 

 not really absent but has undergone a remarkable 

 change, which might cause its presence to be over- 

 looked. At any rate, this is the case in the English 

 family, and from Mr. Farabee's illustrations I feel 

 sure that the American people are exactly like the 

 English family. 



Fig. 2 shows the shape of the two bones in one of 

 these short fingers. The first bone differs from the 

 normal type (Fig. 1) in being shorter, but otherwise 

 it closely resembles it. The second appears to be 

 altogether missing. If, however, the terminal one 

 (Fig. .3) is carefully compared with the normal third, a 

 marked difference will be observed. 



At the base there is seen a cubical mass which is 

 not present in the normal bone (Fig. 1). This cubical 

 mass represents the middle bone, which has become 

 joined by bony union to the terminal one, the two 

 forming one bone in the adult (see 2. 2. 2. 2. Plate 4). 



A radiograph of the hand of an abnormal child 

 shows this middle bone as a distinct and separate 

 structure, but much shorter than the normal (2. 2. 2. 2. 

 Plate 5). It is imperfect also in other respects. Each 

 bone during childhood is only partially " ossified," 

 for there is a piece of gristle lying at the end of each 

 bony portion, and this is well seen in the '' first row " 

 of Plate 5. This gristle during early adult life becomes 

 transformed into bone and fuses with the joint. 



