268 A MANUAL OF DENTAL ANATOMY. 



may recur to the dentitions of non-venomous and venomous 

 snakes. 



In these we saw, in the non-venomous snakes, the max- 

 illary bones covered by a row of teeth sub-equal in size ; 

 then in the ' Colubrine ' poisonous snakes the front tooth of 

 those standing upon the maxillary bone taking upon itself a 

 special and important office, namely, the conveyance into a 

 wound of a poisonous saliva, and coincidently with this 

 tooth attaining its increased size and importance, the teeth 

 behind it on the maxillary bone reduced both in number 

 and in size. Going a step further, to the Viperine poisonous 

 snakes, the now useless small maxillary teeth have all disap- 

 peared, leaving the poison fang alone, and of vastly increased 

 dimensions, to occupy the whole bone. 



But in many poisonous colubrine snakes three or four 

 small and useless teeth lingering upon the maxillary bone, 

 though their function was gone, seemed to indicate to us 

 in some measure the gradual process by which that singu- 

 larly perfect adaptation of means to an end, the poison 

 apparatus of the viper was arrived at. 



It would be impossible in these pages to go through the 

 arguments by which Mr. Darwin has established his main 

 propositions ; it must suffice to say here, that he has fully 

 convinced all those who are not in the habit, from the fixity 

 of early impressions, of putting many matters upon another 

 footing than that established by the exercise of reason, that 

 any modification in the structure of a plant or an animal, 

 which is of benefit to its possessor, is capable, nay, is sure 

 of being transmitted and intensified in successive genera- 

 tions, until great and material differences have more or less 

 masked the resemblance to the parent form. 



Just as man, by favouring the breeding of those modifica- 

 tions of form, &c., that please him best, has been able, in 

 the course of a few years in a length of time altogether 

 infinitesimal, as compared with the time during which the 



