MUNIZ—MC GEE] DEVELOPMENT OF TREPHINING 25 
country, and indeed by the range of current thought in America and 
Europe. Practitioners, like other men, first learn how and then learn 
why to act through action; the zealous physician scans memory and 
record of cases in the effort to find a treatment which gives promise of 
Saving his patient; he can not forget trephining, for the records are 
full of it, his clientele remind him of it, and his rural neighbor per- 
chance practices it on his beast. He can and does weigh the risk as 
shown by the results of empiric practice; he can and does consider the 
physiologic conditions and etiologic bearings of the operation; and in 
the end the operation is performed or not, as the best judgment of prac- 
titioner or consultation may decide. Yet in every case the decision 
is based largely on the record, and the treatment, if adopted at all, is 
adopted largely if not mainly by reason of empirie experience rather 
than by reason of etiologic considerations; indeed, the layman may 
well question whether the desperate operation of trephining (in con- 
tradistinction from simple elevation or extraction of bony fragments in 
case of depressed fracture) would have been introduced before plastic 
and intestinal surgery had it not come down from the prehistoric past, 
a legacy from the darkest ages. 
In this way the genesis and development of one of the most remark- 
able features of medical practice may be traced with a fair if not high 
degree of certainty. The explanation seems safe, because it rests on 
well-established fact at many points; it seems just, because it is in close 
accord with all that is known of the evolution of methods and motives 
among men. The course of development thus traced is not only of 
interest in itself and in its bearings on the trephining of Peru, but is of 
much significance in its relation to the development of other branches 
of surgery and medicine. 
It remains to interpret the Muniz collection in the light of the his- 
tory of trephining as thus outlined, and then to consider the facts 
revealed in this collection as bearing on the history. 
THE CRANIA IN DETAIL 
COMMON FEATURES 
Collectively the crania are notably small and variable in form, as 
indicated by the illustrations, which depict different aspects on a 
seale of two-thirds linear. With one possible exception, all are adult 
and some fully mature, as indicated by the condition of the sutures. 
Considered collectively the cranial bones are remarkably thick and 
strong, only one or two of the specimens approaching the Caucasian 
normal in respect to thinness. The tendon and muscle attachments 
are notably prominent, rugose, and striated, indicating vigorous phys- 
ical development. In several cases the supernumerary interparietals 
known to archeologists as ‘* Inca bones” are found. In one fully adult 
specimen the metopic suture is distinetly preserved; and in general 
the sutures, especially the lambdoid and the posterior portion of the 
Sagittal, are remarkably crenulate. 
