AND NERVES OF THE TONGUE OF THE FROG AND TOAD. 
143 
and thickly studded, as at the dorsum and base of the tongue, the fungiform are like- 
wise long and generally contracted. At the borders and at the tubercles, where the 
papillae conicse are short, the fungiform are thick, short, and surrounded by a thick 
protecting membrane of the same nature as in the papillae conicae, which in the 
lengthened fungiform papillae is much less solid. 
By the application of a minute quantity of solution of potash over a fungiform 
papilla, we sometimes observe a curious appearance. The external zone becomes 
separated from the central area by a deep fissure, and forms a kind of cup contain- 
ing the blood-vessel, which appears like a spiral tube, and within this is seen the 
bundle of nerves. The circulation continues for some time in the papillary vessels 
even in this denuded state, then becomes languid, and finally ceases when coagulation 
of the blood takes place, unless the vessels burst at some point and extravasation 
of blood ensues, which is frequently the case, preventing any further observation. 
The vessels of these papillae are generally derived from arteries and veins, situated 
near the inferior surface of the tongue, from whence they ascend in a vertical 
direction until they reach the pedicel of the papilla. At this point the arterial and 
venous canals appear to be already reduced to the size of the ordinary capillary 
tubes, and they do not appear to undergo much, if any, further decrease of size in 
the capillary tuft at the summit. We might at first imagine that these coils are the 
continuation of one single tube, but such is not the case. They frequently com- 
municate with each other, for when circulation is arrested or impeded in one loop, it 
often continues in the adjacent ones. They contain no valves sueh as are found at 
other parts of the tongue, for after any violent movement of the tongue the circula- 
tion often changes its direction, and what was at first an arterial capillary is after- 
wards found to convey the blood towards the heart like a vein. ' 
Besides blood-vessels and nerves, we invariably discover in the interior of the fun- 
giform papillse numerous striated muscular fibres. They are derived from the super- 
fieial muscular layer, which exists beneath the basement membrane of the dorsum 
of the tongue, and appear to be one of the essential elements of the mucous tegument 
of that region. They run parallel with the vessels and nerves, to which they are 
external, and form a complete investment. After attaining nearly to the summit of 
the papilla, they curve inwards, and afterwards disappear in the surrounding tissueSj 
apparently by losing their striae and sarcolemma, which are their distinctive charac- 
ters. This mode of termination of the fibres is deserving of attention, and is, I 
believe, the only instance in which the gradual transformation of the muscular ele- 
ment into any other tissue than the fibrous variety composing tendons has been 
discovered. I have before mentioned the ciliary motion on the surface of these pa- 
pillae, and its absence over the other papillae which are destitute of muscular fibres. 
We are therefore led to the conclusion that ciliary and muscular power are more 
closely connected than is commonly imagined. The action of these fibres is to 
shorten the papilla, probably at the same time they may compress the vessels, regu- 
