CONTRIBUTIONS TO ZOOLOGICAL ANATOMY. 
597 
Immediately beneath these layers of muscular libres we find 
another layer of comparatively loose cellular tissue surrounding 
the free extremities of the different muscles of the body of the 
tongue. This layer is very vascular, being freely supplied by 
terminal branches of the lingual arteries. 
In some animals, as the chameleon, it is better developed than 
in others; and in this animal forms a distinct layer of erectile 
tissue, which becomes tense and turgid during the sudden and 
rapid darting of the organ on its prey. 
Where it is not so well developed, the rete Malpighi chiefly 
serves the purpose of enabling the superficial lingual muscles to be 
freely and easily moved from before backwards over the surface of 
the tongue, unconnected and unrestrained by the influence of the 
other muscles, from which they are completely separated. Analo- 
gously considered, it is similar in situation and use to the adipose 
layer on the surface of the body, which separates the panniculus 
carnosus from those muscles which are in immediate connexion 
with the trunk, and thereby has its action confined to the common 
investing membrane and its appendages. 
Having thus traced the fibres of the muscles, and seen that they 
are extended along the whole of the upper surface of the organ, 
and fixed posteriorly to the os hyoides, it will be easy to observe, 
that this latter must be the part whence it can become fixed before 
it can be called into action. Taking this, therefore, as its point of 
fixion, whenever it contracts, either by the will of the animal or 
by the presence of some stimulus, it becomes shortened in its length, 
and puckered, as it were, into transverse folds; and it will also be 
observed, that, in consequence of the intimate attachment of the 
anterior extremities of the fibres to the adherent surface of the in- 
vesting membrane, this must also be shortened and wrinkled in 
a corresponding ratio. No sooner, therefore, will this be effected, 
than its immediate and free prolongations, the papillae, will have 
their bases drawn backwards along with it, and with the natural 
consequence of lifting up and tilting forward their apices ; so that 
when the entire muscles are in a complete state of contraction, and 
the investing membrane shortened to its greatest possible condition, 
the whole of the papillae on the dorsum of the tongue are raised up, 
and arranged, as already stated, in nearly regular undulating lines; 
serving thereby as so many tenter-hooks for assisting in laying 
hold of the grass in the herbivora, and forming so many hollow 
channels for lifting up, and containing safely, the fluids in such 
animals as take in this part of their food by lapping. 
The generally received opinion of the action of these muscles, 
viz., “ of bending up the tip of the tongue,” can only therefore be 
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