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XV.— On Variability in Human Structure, with Illustrations, from the Flexor 

 Muscles of the Fingers and Toes. By Wm. Turner, M.B. (Lond.), F.R.S.E., 

 Senior Demonstrator of Anatomy in the University of Edinburgh. 



(Read 19th December 18C4.) 



Deviations from the usually described arrangements of the parts, of which 

 the human body is composed, have from time to time attracted the attention of 

 the anthropotomist. In many anatomical text-books, as well as in sundry 

 memoirs specially devoted to the subject, numerous examples of such variations 

 have now been recorded. To the scientific anatomist these have always had a 

 certain value, but of late years this department of anatomical inquiry, more 

 especially in connection with variations in the muscular system, has had 

 additional importance and interest attached to it, on account of the attention 

 which has been directed to the correspondence, or want of correspondence, in the 

 muscular arrangements in man and the other mammalia, more particularly the 

 apes. 



Into this aspect of the question it is not my intention to enter in this com- 

 munication. My object on this occasion is rather to compare certain structures 

 in one human body with corresponding structures in others, and to point out the 

 extent of variability which may occur in similar parts in different individuals. 



Every one is conscious that of the multitude of individuals he may meet with 

 in the course of a day's experience, no two are alike. Leaving altogether out of 

 consideration all mental differences, each possesses some peculiarity of form and 

 gait which enables him at once to be distinguished from those around him, and 

 that these external manifestations of variability are in their prominent features 

 correlated with internal structural differences will, I suppose, be generally 

 admitted. That diversities in the shape of the skull, for example, occasion cor- 

 responding diversities in the form of the head and face, so as to impart to them 

 characters diagnostic not only of the race, but of the individual, have been 

 recognised from the time of Blumenbach and Camper. But the osseous is not 

 the only organic system in which distinct evidence of structural variability may 

 be traced ; the muscular, vascular, nervous, and visceral systems all exhibit it. 

 In some cases, undoubtedly, the departure from what may be termed the standard 

 method of arrangement, as set forth by descriptive writers, is greater than in 

 others, but evidence of its existence to a greater or less degree in every indi- 

 vidual may be obtained not only by the examination of the systems taken as a 

 whole, but of the separate structures of which they are composed. But though 

 some of the best marked examples of internal structural variations are cor- 



VOL. XXIV. PART I. 3B 



