31 



I therefore present an analysis of an examination of 50 specimens 

 taken indiscriminately as to age and sex. It may be well to state 

 that the material was in every case obtained from the post mortem 

 room, and was examined in the fresh state. The sternum haviug 

 been removed with the costal cartilages a careful dissection was made 

 of fifth intercostal space in the first place, the others being also laid 

 bare and thoroughly cleared of muscular tissue. 



I found that in the 50 specimens examined a joint occurred 36 

 times on the right side, and 25 times on the left side. It is evident 

 then that in the number examined a joint was more often present 

 on the right side than absent, and that so far as the left is concerned, 

 it was as often absent as present. Why there should be this predi- 

 lection in favour of the right side I am not at present in a position 

 to state, but we will see later that in more ways than one it exists 

 very markedly. For when we enquire into the nature of the joints 

 formed between these two cartilages we find that they may be either 

 schizarthroses (diarthroses) or fibroses (synarthroses-syndesmoses). If 

 the right side be the more favoured one we may expect to find the 

 schizarthrosis more often on that side on the left, and in these spe- 

 cimens that is the case, for as a matter of fact it existed 33 times on 

 the right side and 16 times on the left, that is, twice as often on 

 the right as the left side. But going a step further, I find that in 

 those cases in which a schizarthrosis presents itself on both sides — 

 and here it did in 12 cases — the right joint is larger than the left, 

 in fact, it was markedly so in 4 cases out of the 12, in 7 it was 

 appreciably so, and in one case only was the left joint larger than 

 the right. 



Looking at the question from another point of view, and on the 

 supposition that the more favoured side will possess the higher type 

 of joint viz. the schizarthrosis, we would expect to find the fibrosis 

 more commonly developed on the left side than on the right and on 

 examining the table given below we find that a fibrosis occurs 9 times 

 on the left side and only 3 times on the right. 



We have thus four facts in proof of the right side being the 

 favoured one, viz: 



1) The fact that a joint is more often developed on the right side 

 than the left — 36 : 25. 



2) The fact that the higher type of joint exists twice as often ou 

 the right side as the left - 33 : 16. 



3) The fact that when a schizarthrosis is found on both sides, it 

 is larger generally on the right side than the left 11 : 1. 



