FJSCICULI MJL^TENSES 
279 
and, higher still, the cell contents are invaded by anastomosing filaments 
of horn, which originate in the now completely horny walls. These 
filaments grow thicker and more complicated, until, finally, the protoplasm 
is completely obliterated, and the cell limits disappear in a uniform horny 
mass, the conical outline of which is regulated by the fact that a greater 
number of cells is infected by the corniferous stimulus or material in the 
deeper layers of the epithelium than on the surface. A continuous growth 
from below takes place, so that the tooth, as it is worn away on the surface, 
is supplied, gradually and without break, with fresh substance. The 
process of growth can be observed very clearly in a series of longitudinal 
sections of the same individual, but in the material at my disposal the teeth 
are all more or less fully developed, and their exact origin cannot, therefore, 
be ascertained. 
The action and movements of the funnel have already been noted in brief, 
but we are now in a position to discuss them a little more fully. In the first 
place, the absence of vascular tissue of blood vessels, except for the capillaries 
which accompany the muscles, proves that it is not, in the ordinary sense, an 
accessory breathing apparatus ; but possibly it may be connected indirectly with 
the oxygenation of the blood. On three separate occasions I have taken the 
larvae of Megalophrys montana in a small muddy pool, which was liable, on the 
one hand, to dry up altogether, and, on the other, to become part of a rapid 
torrent, generated by a single heavy shower ; and it is obvious that in such a 
torrent an animal which can float lightly on the surface, as the tadpole does 
with its funnel, will be in a very much better position to obtain oxygen than 
one which is being hurried along among the mud and debris near the bottom. 
The tadpole of Rana larutensls^ Blgr., which also inhabits mountain streams 
in the Malay Peninsula, and those of several other species, are provided for 
the same emergency in a different way, bearing on their belly a large sucker, 
which prevents them from being washed away at all and allows them to cling 
to the rocks of the most rapid torrent. The tadpoles of Eeptohrachium hasseltii^ 
on the other hand, have no special need for any apparatus of the kind, for they 
are found, so far as my own experience of them goes, in deep pools at the edge 
of streams in level country, and they only rise to the surface occasionally. The 
main function of the funnel, then, is to act as a float, and, very probably, to 
protect the mouth of the tadpole from the entry of noxious organisms when it 
it burrowing in the mud, as drought causes it to do. It is possible also that 
it assists in the capture of the minute plants and animals on which the species 
feeds, though I can give no direct evidence for this function. If the tadpole 
I. Laidlaw, P.Z.S., LXXXVIII, 1900, p. 886, pi. LVII, figs. 3, 4. 
