ON THE GENERAL MORPHOLOGY OF THE MYXINOID FISHES. 225 
Verbindung stehen, durchsetzt. Zwischen diesen Theilen des Lymphsystems und dem 
‘Pfortaderherzen’ scheint eine Verbindung zu bestehen; aber nur zwei Male war es 
K. gelungen diese Verbindung durch Injectionen darzulegen ; bei dem einen Exemplare 
hatte die Injectionsmasse von den Lymphraéumen aus nicht nur das Pfortaderherz 
selbst sondern auch einen Theil des Venensystems gefiillt.” 
KLINCKOWsTROM’s injections are not as satisfactory or as conclusive as the one 
described above, since he injected not from the portal vein but from the lymph space. 
The fact that the injection reached the portal heart agrees with my results, because the 
mass would reach the latter wa the anterior portal vein (=the right superior jugular). 
3. THe STRUCTURE OF THE VascuLAR PAPILLA. 
The vascular papille, although never entirely absent, vary very greatly both in 
occurrence and structure, and they may or may not open into the surrounding sinus. 
It seems obvious, therefore, that they must be regarded as vestigial structures, and that 
they stand for the vanishing point of the connection between the arteries and the 
lymphatics. 
In figs. 2 to 5 I have represented a series of simple cases in which there was an 
undoubted communication between the cavity of the artery and the surrounding lymph 
sinus. They are all drawn from transverse sections of the arteries, but in fig. 5, owing 
to the greater magnification, only the papilla itself and a small portion of the arterial 
wall are shown. Figs. 2, 3 and 5 are sections of afferent branchial arteries, but fig. 4 
is from the common carotid. The spaces occupied by red blood are indicated by the 
red tint. 
In all cases the base of the papilla is excavated as a large space in free communti- 
cation with the cavity of the artery and which therefore always contains blood. If this 
Space communicates with the surrounding lymph sinus at all it may do so in a variety 
of ways. ‘The apex of the papilla may be more or less pointed and possess a single 
Opening only, as in fig. 3. This is unusual. On the other hand, the free end may be 
expanded, and its external surface indented by a series of crypts, the whole having a 
somewhat digitate or even grape-like appearance, with perhaps one opening or more on 
the summit of each finger. Care must be taken not to confuse these crypts with the 
blood vascular tubules which pass from the basal excavation to the apex of the papilla. 
The latter tubules are usually just large enough to transmit a single corpuscle at a time 
in preserved material, but in the living animal they can be considerably distended. 
Hach papilla may contain only one such tubule, as in fig. 3, or several, as in fig. 5, 
and their relation to each other and manner of opening, when they do open, are very 
variable (cp. fig. 4). The papilla may hence be a simple structure with no more than 
a single opening, or a somewhat complex feature with several openings. 
The afferent branchial arteries on rare occasions give off small vessels to the sur- 
rounding tissues before entering the gills, and in one injection a conspicuous twig arose 
