1890 .] 
475 
[Tuckerman. 
man. The function of these fissures, however, remained unknown 
to him. Two years later Elsasser observed that the sense of taste 
was most intense on the papillae circumvallatae and at a place on 
the hinder part of the lateral edge of the tongue. This place he 
called, quite correctly, the “gustatory fissures” of the tongue. In 
1842, Mayer, unaware of the observations of Rapp and Elsasser, 
described folds in the lingual mucous membrane of man and many 
mammals, and called them papilla lingualis foliata seu interlocularis. 
These folds he regarded as nerve-papillae. It was not, however, 
until 1869 that the true nature of these organs was demonstrated 
by v. Wyss and Engelmann. 
The lateral gustatory organs have been found in the Marsupialia, 
Edentata, Insectivora, Rodentia, Chiroptera, Proboscidea, in sev- 
eral of the Carnivora, and in the Quadrumana. Of the Ruminan- 
tia but three are known to possess them, Tragulus javanicus, Ceph- 
alolop>lius mergens , and Camelopardalis giraffa. In the bandicoots, 
kangaroos, and phalangers of Australia the lateral gustatory or- 
gan may be studied in its most primitive form. In Perameles it 
consists of a single gland-duct, in the walls of which scattered 
bulbs are developed. In Halmaturus , Macropus , Petrogale and 
Dasyurus , there are several of these ducts, with a proportional in- 
crease in the number of bulbs. In Phalangista , Belideus and 
Acrobates , the organ is less simple, and gland-ducts open at the 
bottom of slit-like furrows. Between the complex lateral gustatory 
organ of rodents (in which there is but little to suggest its true 
origin) and these simple types, there are many intermediate forms. 
The microscopic structure of the end-organs of taste of mam- 
mals varies according to their location, and according to the dif- 
ferent species of animals. In general they are not unlike a flask 
or bulb with a short neck ; and they occupy cavities in the epithe- 
lium, which they complete^ fill. Their inner part or base rests 
upon the connective tissue of the mucous membrane. Their outer, 
and more slender portion, perforates the superficial layers of the 
epithelium and opens on the surface with a minute, circular or 
slightly oval aperture. This opening is called the taste pore. The 
margin of the pore is usually formed by three or four cells, though 
it may be formed by two, or, more rarely, as in the fungiform pa- 
pillae, by a single epithelial cell being perforated about the centre. 
The diameter of the taste-pore varies from 0.002 to 0.0045 of a 
millimetre. In the circumvallate papillae the bulbs are disposed 
