358 ON THE ENAMEL AND DENTINE OF THE TEETH 



brana preformativa of the pulp, but internally to it ; Nasmyth's- 

 membrane, which lies over the enamel, being in fact continuous with 

 the membrana preformativa. 



1. On this head, M. Lent adds no new fact or argument of any 

 kind. He simply repeats and confirms the statement already made 

 by Professor Kolliker — that minute gelatinous processes may often 

 be found passing from the surface of the pulp into the dentinal canals- 

 (a statement which no one denies), and then takes for granted 

 Professor Kolliker's purely hypothetical interpretation of this fact — 

 i.e., that these processes are outgrowths of the " cells " of the surface of 

 the pulp — an hypothesis which is not supported, so far as I am 

 aware, by a shadow of direct evidence ; and it is to be remembered 

 that the_/(?rfis as well accounted for by my h3'pothesis as by any other.. 



So much for the formation of the dentinal tubules. With regard 

 to the substance of the dentine, M. Lent does not seem to have seen 

 much more than myself; for he says that "it is more probable — 

 indeed certain " that the " grund-substanz " is an " excretion of the cells 

 and their processes'' (P. 127.) 



That is to say, M. Lent (i.e. Professor Kolliker) admits that there 

 is no new evidence to be brought forward as to the formation of the 

 dentine tubules, and that the substance of the dentine is formed as I 

 have stated it to be. Truly, then, I do not see where the " irrige 

 ansicht" with which I am charged lies. 



At page 128 there is a very careless misstatement, which one 

 might be disposed to overlook in a student, but which is utterly 

 unpardonable in a production which has the advantage of Professor 

 Kolliker's deliberate imprimatur. 



" As regards Huxley's erroneous view as to the formation of the 

 dentine, I will only briefly remark, that Huxley has been so unfor- 

 tunate as to have seen the dentine from above only." (p. 128.) 



This is truly astounding, considering that at page 160 of my paper 

 I give particular directions how to obtain a profile view of the dentine 

 in undisturbed connexion with the pulp ; that figs. 3 and 4 are 

 careful representations of such profile views ; and that I lay par- 

 ticular stress upon the advantages to be derived from this mode of 

 examination. 



2. With regard to the development of the enamel, M. Lent {i.e. 

 Professor Kolliker) affords a confirmation of my views ; all the more 

 valuable, as it is evidently most unwillingly wrung from him. 



At page 129, M. Lent, after stating the ordinary theory of the 

 development of the enamel, says : " This simple theory must, however,. 

 I believe, be given up, since Huxley has made a discovery whose 



