378 Harris Hawthorne Wilder 



or some other slight cause responsible for the original decision. It would 

 be of much interest to examine the intestines of other Jani and see 

 whether one side is preferred for the meconium, whether, if this he the 

 case, the unused side becomes separated from the other, and whether 

 the same side is alwa^ys preferred. This latter point could of course be 

 determinable only in cases with some lateral torsion, and in view of the 

 varying relation of the aortic arches in different specimens, as described 

 below, it is most unlikely. The cutting off of A's intestine, in view of 

 its perfect development otherwise, appears to have been a late event, due 

 to some mechanical cause, and in no way the result of a primary inequality 

 in the two components. 



It has been claimed for certain cases of duplicate twins that, in some 

 particulars at least, they are the symmetrical equivalents of each other, 

 but in this case, at all events, the two components are not thus related, 

 but each is perfectly normal in this respect. Thus the appendix of A 

 lies superficially upon the perfect side, and that of B upon the imperfect, 

 the right side of each component, and the same thing is shown by the 

 spleens, which lie diagonally with reference to the double stomach, but 

 each upon the left side of the component to which it plainly belongs, and 

 therefore noriual in its relations. The double liver is an enormous 

 organ, and upon each aspect covers the entire width of the visceral 

 cavity. The face of this mass seen upon the perfect side consists of the 

 right lobe of A, with the gall bladder of that component, and the left 

 lobe of B, without a bladder; the opposite face, that of the imperfect 

 side, which at this level is nearly as wide as the other, is composed of 

 the right lobe of B, with its gall bladder, and the left lobe of A, without 

 one. In these organs, then, except for the continuity of the liver 

 masses belonging to the separate components, the relations are the normal 

 ones which would be found in two separate individuals that stand facing 

 each other, and show no trace of looking-glass symmetry. At this level, 

 also, the other organs are mainly individual, and not shared by the two 

 components. 



As a detailed study of all the parts of this specimen is not possible 

 here, we may select two, the details of which seem to present especially 

 good material for discussion: (1) the middle ear of the synotic side, with 

 its included ossicles, and (2) the heart and the larger blood-vessels. The 

 first of these is a part that has not yet become functional, and would 

 thus naturally be expected to show the primary and unmodified symmetry 

 characteristic of a typical Cosmobion; the second is one that shows the 



