1878. ] The Sensory Organs. 585 
Wysen, about 1870 (A. f- M. A. vi); von Ajtai in 1872 (A. f. M. 
A. vii); Honigschmied in 1873 (Z. f. W. Z. xxii), who also noted 
the occurrence of taste-buds on the free or upper surface of cir- 
cumvallate papilla, though their presence here was not constant 
and they were generally smaller than those found onthe sides. 
He says, also, that there can hardly be any doubt regarding the 
continuity of the taste-cells with nerves. In chloride ‘of gold 
preparations from the cat he traced the nerves directly into the 
buds, and what is worthy of remark, the cover cells were mot 
stained by chloride of gold, while the taste-cells were. 
Before proceeding any farther, it will be necessary for the cor- 
rect understanding of the view I wish to present, to consider 
some organs not possessed by man. 
In fishes and amphibians we find a set of organs whose sensory 
character was first claimed by Leydig in 1850 (M.A). I refer to 
the so-called “mucous canals.” In 1861, F. E. Schulze (/did.) 
re-described these organs as containing small cellular elevations, 
from which arise a number of stiff parallel hairs, which reminded 
both him and Leydig of the auditory hairs. A profile view of- 
the typical structure, according to Schulze, reveals a hyaline cyl- 
inder generally much longer than the hairs, which it encloses and 
to which it allows free access of water. In speaking of the rela- 
tion which the nerve fibres bear to the cellular elevations, he says: 
“In the lower layer I see round cells . . . . . These I take to be 
connective tissue cells. Between these last we see in fishes of a _ 
certain degree of development (15 mm. and over), sharply con- 
toured nerve fibres which are given off from the nerves approach- 
ing the elevation. After they have passed between these cells 
they terminate by means of a “ conical narrowing” in the above 
mentioned hairs. This is most readily seen by fixing the eye 
upon a single hair and then following the inward continuation of 
the same. In so doing we recognize as the base of the hair a con- 
ical body which protrudes over the epithelial surface. . . . This 
little ten-pin-shaped body (Kegel) we again recognize as the nar 
rowing of a nerve fibre lying between the epithelial cells....... 
In 1870 (A. f. M. A.), F. E. Schulze re-investigated these organs, 
and made some important additional statements. What he had 
_ previously described as a ten-pin-shaped narrowing of the nerve | 
_ fibre into which the hair is inserted he now describes as a nucle- 
ated cell; 7, e. he now describes as the ultimate sensory ere 3 
