272 
DR. U. PRITCHARD OH THE COCHLEA 
epithelium but packed closer together. Numerous blood-vessels traverse the layer 
but never appear quite on the free surface. As the form of epithelium, which 
is modified so as to receive the terminations of special nerves, is called “nerve 
epithelium/’ that of the stria vascularis might, I think, be very appropriately called 
“ vascular epithelium.” 
The epithelial lining has now been traced back to the membrane of Reissner, 
and thus right round the tube, with the exception of the organ of Cortt, which 
has now to be described. 
As the organ of Corti of the Ornithorynchus (see Plate 46, fig. 6) closely resembles 
that of the ordinary Mammal, which I described in a paper read before this Society in 
1876,* I propose to give merely a brief sketch of its structure, and later on to note 
how it differs from the typical Mammal. 
The organ of Corti consists of two rows of rods separated from each other below, 
and united at their upper extremities, thus forming with the membrana basilaris, on 
which they stand, a triangular tunnel. 
Each of the rods have enlarged upper and lower extremities ; the latter are similar 
in both rods, being simply enlarged feet. But the form of the upper extremity differs 
in the two rows ; in the rods of the outer one it is oblong, with a delicate process pro¬ 
jecting inwards from its upper part. The upper extremity of the inner rods is more 
rounded and fits into a shallow concavity of the head of the outer rod. From 
the upper part of these inner rods there is also a delicate process projecting inwards 
and lying below that of the outer rod. The shafts of both rows of rods are cylindrical 
and of equal size. 
On each side of the rods are arranged rows of cells, there being a greater number on 
the inner side (the side next to the ligamentum cochleae). The most important 
of these are the hair or bristle cells which are arranged in four rows ;t one row to the 
outer side of the outer rods, and three rows to the inner side of the inner rods. 
These bristle cells are elongated with flattened upper extremities and rounded lower 
ones; their outline is well defined, and they contain a well-marked rounded nucleus ; 
from their summit projects a row of four or five bristles. 
* ‘ Proc. Roy. Soc.,’ vol. xxiv., p. 346. See also— 
U. P., “ Structure and Function of the Rods of the Cochlea,” ‘Monthly Micros. Journ.,’ 1873. 
U. P., “ Development of the Organ of Corti,” ‘Journ. of Anat. and Phys.,’ vol. xiii. 
Waldeyer, “ The Cochlea,” Stricker’s ‘Histology,’ vol. iii. 
Lavdowsky, “ Untersuch. ii. d. Akustichen Endapparat. d. Saugeth.,” ‘Archiv. Micros. Anat.,’ p. 497, 
Bd. xiii., 1877. 
Bietxcher, “ Ueber Entwick. u. Bau des Gehorlaby. u. Untersuch. a. Saugeth.,” Nova Acta, Leopold. 
Acad., Bd. xxxv. 
Gottstein, “ U. d. fein. Bau u. d. Entwick. d. Gehorschnecke d. gaugeth.,” ‘Archiv. f. Micros. Anat.,’ 
Bd. viii., p. 145. 
Winiwarter, “Untersuch. ii. d. Gehorschn. d. Saugeth.,” ‘Wien. Akad. Sitzber.,’ Bd. lxi., 1 Abth., 
p . 683, 1870. 
f See postscript for the account of an additional row. 
