VIIL] HOMOLOGIES. 205 



at its origin, the two halves re-uniting at the elbow-joint, 

 and then dividing into the radial and ulnar arteries in the 

 usual manner. In the second case an aberrant artery was 

 given off from the radial side of the brachial artery, again 

 almost at its origin. This aberrant artery anastomosed 

 below the elbow-joint with the radial side of the radial 

 artery. In each of these cases the right ancl left sides 

 varied in precisely the same manner. 



Thirdly, as to pathology. Mr. James Paget, 1 speaking of 

 symmetrical diseases, says : " A certain morbid change of 

 structure on one side of the body is repeated in the exactly 

 corresponding part of the other side." He then quotes and 

 figures a diseased lion's pelvis from the College of Surgeons 

 Museum, and says of it : " Multiform as the pattern is in 

 which the new bone, the product of some disease com- 

 parable with a human rheumatism, is deposited a pattern 

 more complex and irregular than the spots upon a map 

 there is not one spot or line on one side which is not re- 

 presented, as exactly as it would be in a mirror, on the 

 other. The likeness has more than daguerreotype exact- 

 ness." He goes on to observe : " I need not describe 

 many examples of such diseases. Any out-patients' room 

 will furnish abundant instances of exact symmetry in the 

 eruptions of eczema, lepra, and psoriasis ; in the deformi- 

 ties of chronic rheumatism, the paralyses from lead; in 

 the eruptions excited by iodide of potassium or copaiba. 

 And any large museum will contain examples of equal 

 symmetry in syphilitic ulcerations of the skull; in 

 rheumatic and syphilitic deposits on the tibiae and other 

 bones ; in all the effects of chronic rheumatic arthritis, 

 whether in the bones, the ligaments, or the cartilages; 



1 "Lectures on Surgical Pathology," 1853, vol. i. p. 18. 



