DEVELOPMENT OF VASCULAR DENTINE. 
29 
This is well seen in fig. 2, which is a section of dentine cut with a sharp knife from 
the tooth of a Hake within a couple of hours of its capture. From the edge of the 
dentine there hang out (at cp) torn capillary vessels, from the ends of several of 
which hundreds of blood corpuscles were slowly flowing out as I was making my 
drawing. The section was also sufficiently thin to allow of the blood corpuscles 
contained in the capillaries within the dentine to be distinguished through its 
substance, as is seen in the figure. 
This dentine may therefore be most appropriately called Vaso-Dentine, and no 
better name could be found by which to designate it ; but I confess myself unable to 
see what useful purpose can be served by the rich vascularity of the dentine ; it would 
seem improbable that the dentine should need nutriment, for the teeth of the Hake, 
like those of most fish, are obviously frequently shed off and renewed, and there are 
five or six teeth in preparation for every one that is in place and at work. And this 
rich plexus of capillaries is the less intelligible as the intervening dentine is of 
unusually dense and impermeable structure, and, one would think, was as little in 
need of vascular supply as anything which remains in continuity with a living 
organism could well be. 
In the clear external layers of dentine a very faint striation perpendicular to the 
surface can be made out, but I have entirely failed to make out the existence of any 
thing like tubes in it, whether by the use of powers as high as a ^-nd objective, or by 
the endeavour to get coloured fluids to penetrate them. I am pretty well satisfied 
that no tubes exist, but that the indistinct striation is simply a result of the manner in 
which the tissue was developed, as will be presently described. 
In addition to the markings just alluded to, there is a faint striation of the whole 
dentine in line, roughly speaking, parallel with its surface. lake the striation of the 
peripheral dentine, these lines probably do not represent any tube system ; but may be 
due to successive depositions of calcified material on the interior of that already formed, 
and mark lines of growth. 
A tooth which has been decalcified shows sometimes a tendency to split up along 
these lines, but although I have used a variety of processes and examined very fine 
sections taken in many planes, I cannot make out the existence of actual tubes in the 
interspaces of the large capillary canals. But the vascular canals are so close together 
that there is comparatively little interstitial tissue, and the nature of the dentine 
matrix may be more advantageously studied in the teeth of other Gadidee, such as 
the Cod, in which the vascular loops are not quite so close to one another, and in 
describing the teeth of that genus I shall recur to this matter. 
The pulp of the tooth of a Hake is, like its dentine, remarkable for its vascularity ; 
at first sight it appears to consist of nothing whatever besides blood-vessels and 
odontoblast cells, the latter being upon the surface. More minute examination reveals 
the existence of a very delicate connective tissue binding it all together, but the 
great bulk of it really does consist of blood-vessels. 
