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portion of the navicular, modifying its shape very characteristically; 

 but what Pfitzner says nothing about is that also very frequently it 

 is seen on both bones at once. In fact it is often very hard to decide 

 whether a slight prominence on the cuboid is of any significance or not. 



It is a very curious fact that while this double appearance of an 

 element is unmistakeable in certain bones, those I have mentioned and 

 perhaps some others, yet certain elements have never, so far as I 

 know, been observed in two places at once. The intermetatarseum is 

 an instance, usually it is not represented. It is most frequently 

 seen as a prolongation of the internal cuneiform, then as a separate 

 bone, then as a process from the second metatarsal, and finally as 

 joined with the first metatarsal. There is a curious family resemblance 

 of all the instances which I have observed of its fusion with the 

 second metatarsal, and the same is true of those figured by Pfitzner. 

 Every single case looks like a pathological exostosis. 



The last paragraph is perhaps a digression. Let us return to the 

 main question. Another criticism to which the theory is exposed, as 

 has been hinted at in what goes before, is the difficulty of unterstand- 

 ing why some projections should indicate originally distinct elements 

 while others should be simply outgrowths. One would say, for in- 

 stance, that the head of the astragalus is of sufficient importance to 

 be an original element, and yet it seems to be only the result of a 

 modification of the shape of the astragalus. 



If this be so it brings into prominence an important fact, namely 

 the readiness of the elements to change their shape according to 

 circumstances, which is perfectly analogous to the results of experi- 

 ments on lower forms in which after mutilation of the embryo, certain 

 cells, in their efforts to produce as normal an individual as is pos- 

 sible under the circumstances, form tissues and structures quite dif- 

 ferent from those which they would have produced under normal 

 circumstances. Moreover, it seems that this effort at repair may be 

 the explanation of what occurs when we find one of the carpal or 

 tarsal elements in two places at once. Let us suppose that the 

 styloid (according to its habit in mammals generally) has fused with 

 the OS magnum and nevertheless the third metacarpal presents a rudi- 

 mentary styloid process. This must be due to the effort (so to speak) 

 of the organism to develop in the way that is normal in man. That 

 there is such a tendency in the living organism is beyond question. 

 This is only one of many of its manifestations. When, however, the 

 styloid is represented equally well on both bones no one can tell what 

 has become of the original element. 



Anat. Anz. XXXV. Aufsätze. 24 



