40 EINAR LÖNNBERG, STUDIES ON RUMINANTS. 



be used as weapoBS and show mechanical arrangements in order to withstand breakage, 

 bending, torsion, corrugation and other disturbing influences, to which they are subjected 

 in the struggles in Avhich the animals are involved, it may be against rivals of the same 

 species or other adversaries. Those adaptations are different in different forras ^) and may 

 be suramarized and recapitulated in the following lines. The most primitive and simple 

 alteration of the original form is when the otherwise homogenous core becomes compressed 

 in snch a way that the axis of its section gets prolonged in the plane of attack as for 

 instance in Bhaphicerus, Antilocapra etc. ^) This alteration is still more suitable if the 

 section becomes ovate as in Saic/a, Cervicapra etc. or triangulär as in Tragelaphus and 

 Strepsiceros, that is a moditication to the likeness of a T-beam. These changes may take 

 place withoLit any other saving of material being made than that which lies in the pro- 

 duction of a greater effect with the same material by means of the altered shape. Nothing 

 is done to lessen the weight of the horn. A saving of material which at the same tirae 

 lessens the weight seems to show itself first in the base of the horn, which is subjected 

 to the greatest force, because it is the end of the lever. In placing the resistant material 

 peripherically, so that a tube '"*) is formed, firmness is gained and the material of the central 

 parts can be dispensed with more or less. The first tendency towards a partial loosening of 

 the centre of the base may perhaps be traced in Cervicapra (porosity) but is more con- 

 spicuous in Gazella (sponginess) and still more so in Strepsiceros, where the spongious 

 tissue in the centre of the base is very tine. The next step is the development of a real 

 cavity. Such a one is found in Tragelaphus, although small. In Antidorcas the basal 

 sinus is well developed, and so it is in Hippotragus, Oryx, Rupicaprince, Ovibos and Buha- 

 lince. By and by the horny sheath has become more strongly developed and gained in 

 resisting power. In consequence hereof a loosening of the distal parts of the core has 

 been made possible and can take place without danger in some horns. *) The core of 

 Gazella is thus spongious, but in an almost tubular manner. When it has gone so far 

 that the core has begun to be spongious, it is favourable especially in horns much used 

 in fighting if the material, nt the same time that it is loosened, is arranged so as to be 

 most effective. The least regular and only little conspicuous trajectories according 

 to Culmann's law are found in Hipp)Otragus. In Antidorcas they are already better 

 visible in some parts, and in Ovibos, Kupicapra and Bubalis they are very beautifuUy 

 developed. The tendency of lessening the weight of the horn is expressed very plainly 

 in Oreas, too, but in a different manner. The distal part of the core is transformed to 

 a tube including a large cavity. In Oryx the core forms a tube, as well, and the inner 

 spongiosa especially in the distal parts is extremely loose and only slightly developed. The 

 development of true sinus in the core stånds of course in connection with the develop- 

 ment of the sinus in the frontal bones. In horn cores growing on quite compact frontals 



1) In such cases wheu the geuera iiiclude several species the remarks refer, of course, to such forras of 

 which I have had material. 



^) And in connection with other modifications in Gazella, Hippotragus, liiipicajn-a. etc. 



^) The importance of the uubroken firmness of the peripherical layers has in compact horns already 

 found an exprcssion, when the canals for the maiu bloodvessels are located at the centre {Cephalojthus, Anti- 

 lope, Strepsiceros). 



*) But horns with a thin sheath retain the compact core e. g. Tragelaphus (compared with Oreas). 



