I. Oii tlie structurc of tlie horns of Cavicoriiia. 



Wliile occupied in the study of the dcvelo|jiiieut of the honis of the musk-ox on 

 the luaterial l)rought hoiiie by Professor A. G. NATiiOKST's Expedition to East Grecidand 

 1899, I observed in the liorn-cores of the niusk-ox and sonie other rumiuants sonie 

 structures which aroused niy interest. There were, nainely, to be seen certain arrange- 

 iiients of the bony material which seenied to uie to ofter sorae analogy to the iiieeliaiiical 

 structures found in various l)ones of the skeleton in accordanee with Culmann's ingenious 

 laws of pi-essure and pull. The niechanical structure of ditlerent skeletal parts has l)een 

 described by se\cral authors Meyer, Wolff,') Z.schokke,-') Hultkkantz, ') Scmmidt,"*) and 

 others. I refer to the lists of literatui'e of the two last uicntioned authors, the latter of 

 which has, not long ago, published the [japer quoted, which also contains a sketch of the 

 history of this Ijranch of study. So far as 1 know, however, the study of the niechanical 

 sti'ucture has not been extended to the horn-cores and I presunie therefore that the 

 following short account mav be of interest. The mechanical structure of the core 

 is the more remarkable, because its function differs so iiiucii from that of the skeletal 

 l)ones. The latter have, namely, to endure an almost permanent pressure in carrying 

 the weight of the body or, as Z.schokke (1. c.) points out, are iiiHuenced by tlie muscles 

 and ligaments. As an example of the latter kind he mentions the arms of man and the 

 hindlegs of seals, »welche doch fur gewöhnlich nicht belastet werden.» The horn-cores 

 of the Cavicornia, on the other hand, cannot receive any impression from either of these 

 two kinds of agencies. They are only subjected to pressure for comparatively short 

 moments when they are used as weapon.s or otherwise and have only to carry their own 

 weight during the meantinie whicli is of course (at least as a rule) so insigniticant that 

 it does not need and cannot cause any special niechanical arrangements. 



It seems accordingly evident that the structure of the cores cannot be due to any 

 agency working solely or chiefly during the life of the animal itself. Wlien the horns 

 are needed and used they must already have a(|uired sufticient strength and be ready 



') Virubows Arkiv. Hd. I, etc. ' ' ' - '' ■• ' ' > ■ ; 



-) Wfitere Uiitersiichunf,'en liber das Verhiiltuiss der Kuocheubilduiig, Ziirich IH'.)-'. :•■' ; • 



■*) Das Klleiibogeiigelenk und seine Mekauik, 181)7. 



■') Vergl. Anat. Studien Uber den Dau der Knocheii und seine Vererbuiig, Zeitschr. f. Wiss. Zool. Bd. 

 65. 1899. 



