46 MARGARET H. COOK AND H. V. NEAL 
and poor vision. In Squalus acanthias, a very active form, 
taste-buds are limited to the mouth and pharynx. Here they 
arise in the epithelial lining of the floor, the roof and the sides, 
including the visceral arches. They are first visible when the 
embryo is about 40 mm. in length. They are numerous and 
extend forward on the roof and floor of the pharynx to the region 
of the upper and lower jaws and posteriorly to the papillae of the 
oesophagus. Their distribution shows clearly in a ‘pup’ stage 
such as is represented in figure 28 of this paper. 
The structure of taste-buds in Squalus acanthias is similar to 
that described for other vertebrates. They occur upon small 
papillae projecting slightly above the surrounding epithelium. 
The papillae are covered with a many-layered epithelium similar 
to that which covers the surface of the pharynx. At the apex 
of the papilla, however, the epithelial cells are modified into 
long, slender ‘sense-cells,’ each of which terminates externally 
in a short hair-like projection. Nerve fibers may be traced to 
the bases of such cells. Figures 1, 2, and 3 of this paper show 
three stages in the differentiation of taste papillae and ‘buds.’ 
Bateson (’90) and Nagel (’94) were the first to attempt to 
demonstrate the function of these structures by experiment. 
They worked on a number of forms, including two dogfishes, 
Scyllium canicula and 8. catulus. Bateson describes the distri- 
bution of taste-buds in the dogfishes as limited to the pharynx, 
although he adds that he would not presume to say that they may 
not be found also on the outer surface of the body. He failed 
to demonstrate that they play any important part in food-getting. 
This process, according to his observations, is controlled by the 
olfactory organ. Nagel, using dilute solutions of sour, bitter, 
and salty substances for taste, finds that the sense of taste is 
but feebly developed in Scyllium. He concludes that a sense 
of taste, such as in most animals is located in the mouth, is absent 
from the outer skin of all fishes. 
Recent work by Sheldon (’09) on the smooth dogfish, Mustelus 
canis, which resembles 8. acanthias in having the taste-buds 
limited to the pharynx, shows that these organs are concerned 
in reactions to the stimulus of bitter substances. To quinine 
