359 



CORRESPONDENCE 



THE EVOLUTION OF HORNS 



Mr J. T. Cunningham's article is too long for detailed criticism in the correspondence 

 columns of Natural Set',, ire, but perhaps I may be permitted to meet his remarks con- 

 cerning horns. I take it that the Neo-Darwinian theory of the evolution of horns is as 

 follows. Other things equal, when the hornless ancestors of horned ruminants first 

 began to fight by butting, those individuals best succeeded in the struggle which had 

 skulls most adapted for that mode of combat, i.e. those which had the thickest and 

 toughest frontal bones. The next step, after the evolution of strong and solid frontal 

 bones, was the survival of such individuals as had bosses of bone where the impact of 

 the blows most fell. Lastly, the continual survival of those that had the bosses best 

 developed led in time to the evolution of antlers. In the Bovidae a casing of cornitied 

 skin was evolved in addition to the bony projections. 



Mr Cunningham asks, ' ' Firstly, why do the antlers only begin to develop when the 

 stag becomes mature. Secondly, why are they renewed every summer and drop off in 

 spring." The answer appears to me simple. As he says, " it is at least significant that 

 the males only fight when they begin to breed, and when mature only in the breeding 

 season." It follows, since antlers are used only during the breeding season, that at all 

 other times, being very heavy and cumbersome, they are not only useless, but much 

 worse than useless. They are then causes of elimination only. Natural Selection 

 has, therefore, not only evolved antlers, but has also fixed the times of their appear- 

 ance. They are not needed by the immature stag, and therefore he has them not. They 

 are not needed by the mature stag after the breeding season and therefore he sheds 

 them, just as in cold climates animals shed their winter coats when the return of spring 

 renders these not only useless but worse than useless. The horns of the Bovidae being 

 much lighter are much less cumbersome than antlers, and for that reason are not shed. 



Mr Cunningham attributes the evolution of horns to the stimulation of butting. 

 The primary objection to this is that which applies against all arguments for the trans- 

 mission of acquired traits, viz., that it is highly improbable that alterations in the soma 

 can alfect the germ cell in such a manner that the parental modification is produced in 

 the descendant organism : in other words, it is highly improbable that the modification 

 which butting produces in the frontal bone of the stag can so affect his spermatozoon, 

 situated as it is far distant, that after long separation from the parent organism and 

 union with another germ it develops into an individual which has inborn the special 

 peculiarity the parent acquired. A priori the transmission of acquired characters seems 

 impossible, and the onus of proof therefore rests with the upholders of the Lamarckian 

 doctrine. Suffice it to say that the organic world has been ransacked, and no indubi- 

 table instance of such transmission has ever yet been proved. Moreover, there is a 

 special objection to Mr Cunningham's theory concerning the evolution of horns, viz. 

 this, that horns do not grow under the stimulation of butting as he seems to imply. 

 Both in the young deer and the adult they complete their growth before the animal 

 begins to fight ; during the fighting season they do not increase a grain in weight. If 

 then use, i.e. stimulation, does not cause their development in the individual, it cannot 

 of course have caused their evolution in the species. ( ;. Aechdall Reid. 



9 Victoria Road, Southsea. 



VACCINATION 



In the note in September's Natural Science on the above subject, it is stated as proved 

 that vaccinia is merely attenuated small-pox. Prof. Crookshank, in his "Bacteriology 

 and Infective Diseases," fourth edition, 1896, in reference to experiments made to prove 

 the identity of the diseases, says: "The results of these experiments have been very 

 generally misinterpreted, and claimed by some as conclusive evidence of the identity of 

 cow-pox and small-pox. Instead of the vesicle being regarded as the most attenuated 

 form of variola, the experimenters are said to have succeeded in producing cow-pox. It 

 is quite true that they produced phenomena indistinguishable from the phenomena of 

 an ordinary vaccination, but that does not mean that they produced the disease cow- 

 pox. The vesicle which followed the inoculation, whether papular or vesicular, was 



