GROWTH OF THE INNER EAR OF ALBINO RAT 153 



Organ im wesentlichen fertig ausgebildet. " They publish no 

 measurements nor data. The condition of the development of 

 the organ of Corti described as 'fertig ausgebildet' is not suffi- 

 ciently precise. 



Further, on the same page they say, "Der auffalligste und, 

 soweit die Untersuchungen bis jetzt eregben haben, einzige 

 Unterchied, der zwischen dem anatomischen Bild des Labyrinthes 

 eines neugeborenen Tieres, das den Reflex eben nochnichtaufweist, 

 und dem eines solchen, dasdenselben zum ersten Male eben erkenn- 

 an lasst, ist der, dass beim ersteren noch ein Zusammenhang zwis- 

 chen Cortischem Organ und Cortischer Membran besteht, beim 

 letzteren dagegen dieser Zusammenhang bereits gelost oder gelock- 

 ert ist." Their observation is quite different from mine. In my case 

 the papilla spiralis shows in the development of its constituent 

 elements pretty large differences between the not-hearing and 

 hearing rats. Therefore it seems probable that the changes in the 

 growth and form of the papilla just before the first appearance of 

 the special function, take place very quickly. Also we cannot 

 agree to then* statement concerning the relation of the membrana 

 tectoria to the papilla spiralis. In our preparations there is 

 still a connection of the membrane with the terminal frame of the 

 lamina reticularis through a thick thread in the cochlea of the 

 rat which could hear (fig. 8) and also in that of the rat which 

 could not hear (fig. 7). 



This is a point on which opinions differ. While one opinion, 

 represented by Kishi ('07) and others, is to the effect that this 

 connection remains through life, the other, represented by Koll- 

 iker('67) and others, asserts the membrane projects free in the 

 endolymph. I have never seen this connection in the adult 

 cochlea, nor have I found such a connection of the membrane 

 with the hairs of the hair cells, as Shambaugh ('10) described in 

 the pig. In the young rats, at fifteen days for example, we very 

 often see upon the terminal frame the broken remainder of this 

 connecting thread. Whether this break arises through natural 

 development or is the result of artificial manipulation it is hard 

 to say. At any rate, Held's assertion ('90), that in an animal 

 capable of hearing the membrana tectoria is never connected 



