THE DEVELOPMENT OF THE TEETH. 141 



be perplexed in endeavouring to reconcile the statements of various 

 authors, to give a succinct history of the views from time to time 

 set forth. Q 



Before the time of Goodsir (1838). the development of the teeth 

 was described by Kaschkow somewhat vaguely as proceeding under- 

 neath the mucous membrane, he did not, however, trace out in 

 what precise manner the several parts of the tooth germ originated. 

 The papers of Goodsir giving, in the place of somewhat vague and 

 general notions, a very definite and intelligible description of ob- 

 servations, was accepted without question by most anatomists, if 

 not by all. Accordingly we find in all the text-books at and after 

 that period, and in some even at the present day, the description 

 given by Goodsir reproduced almost without alteration, so that it 

 will be worth while to briefly relate what his views were. 



He believed that at an early period in foetal life there appeared 

 a continuous open groove, running round the whole circumference 

 of the jaws ; that from the bottom of this groove there arose iso- 

 lated and uncovered papillas, corresponding in number to the milk 

 teeth ; that these papilla? became covered in by the deepening of 

 the groove and the meeting of its two edges over their tops, whilst 

 at the same time transverse septa were formed, so that the several 

 papillae became enclosed in their own separate follicles. With the 

 details of the process as described by him we are not concerned ; it 

 will suffice to remember that he distinguished the four stages ; a 

 primitive dental groove, a papillary stage, a follicular stage, and an 

 eruptive stage (the latter of course at a long subsequent period). 



Not only were these views accepted quite without question, but 

 they were even extended to explain the development of the teeth 

 in Reptiles and Fishes, and thus in the Odontographies of Professor 

 Owen and Professor Giebel may be found accounts of the develop- 

 ment of the teeth in reptiles and fish which are perfectly in accord 

 with Goodsir's theory, but which in fact are far more inaccurate 

 than the same theories were as applied to mammalian teeth. 



Even so careful a writer as Professor Huxley, who was the first 

 to point out that these stages really did not exist either in the frog, 

 the mackerel, or certain other fish, accepted them without question 

 as true of mammalia. Marcusen ( 2 ) (1849) gave upon the whole a 

 correct account of the process, referring the enamel to the oral epi- 

 thelium, and Professor Huxley (1854), whilst demonstrating that 

 the stage of free papillae was not to be found in certain fish and 



( ! ) After the present summary had been partly prepared, the author 

 met with the very excellent rsum6 given by Messrs. Legros and Magitot, 

 from which he has received much assistance. 



( 2 ) In the resume given by Messrs. Legros and Magitot, before referred 

 to, due credit is not given to the papers of Marcusen and Huxley (1849, 

 1854) (although they are alluded to), and it appears to me that too much 

 is given to that of Natalis Guillot (1858). 



