38 
DE. a. KOLLESTON AND ME. C. EOBEETSON ON THE AQTJIEEEOTJS 
foot-mass in common with and interposed between the red, its larger trunks holding the 
same position relatively to the larger red trunks as the larger systemic veins do to the 
lai'ger generative ducts, but it has spread itself into the gills, which the red fluid has not. 
Experiment 8. — A similar one to the preceding, but that the blood-vascular system 
was distended with the fluid used in Experiment 7 for the aquiferous, and vice versa. 
The red fluid was thrown in by the aorta, it filled a large artery running parallel with 
the cap of the foot, it filled both labial tentacles, and it set, as it stiffened, in bossy 
masses along the edge of the foot, lastly it returned to the venous sinus and filled it 
and the organ of BoJANUS, — occupying thus the entire systemic and renal-portal vessels. 
The blue cold injection was thrown in by the orifices through which the generative 
products are extruded ; and we shall see that it, when thus thrown in, disclosed the 
existence of a system of vessels distinct from those already so clearly marked out as 
coextensive with the systemic vessels. It spread itself chiefly over the ovary, but formed 
a fine plexus along the free edge of the foot beyond the artery described as running 
parallel with the edge of the foot, and figured as doing so by Langer*. 
This experiment must be thought to go a considerable way towards demonstrating 
the existence of a system of tubes distinct from, however closely apposed to, the blood- 
vascular system, — this system having been, in this experiment, filled with a rigid mass, 
and filled with it most thoroughly, as the injection of the organ of Bojanus proves, and 
yet allo'uing the trees injectible from the aquiferous outlet to coexist side by side with 
it, even though the fluid they contained was so much more easily displaced than the 
stiffening size injection. 
Thh’dly, of triple injections. 
The readiness with which injections pass from the arterial into the venous system 
make the triple mjections which we have practised of less physiological value than at 
first sight might appear to be the case ; and consequently we will content ourselves with 
gfring the details of one such injection. 
Experiment 9. — A large Anodon was injected from the venous sinus with a yellow 
stiffening injection; after this had been done, a blue-coloured fluid, also with size for its 
basis, was thrown into the aorta; and thirdly, a red injection of the same character was 
thrown in by the aquiferous opening. The blue fluid thrown into the arterial system 
drove the yellow fluid before it out of the systemic veins almost entirely, but it did not 
follow it into the renal-portal system of the organ of Bojanus ; this organ and the gills 
remained richly injected with yellow, to the exclusion of both the other colours ; the red 
fluid, finally, which was thrown in by the aquiferous opening, spread itself in couples 
with the arterial blue over the entire visceral mass, filling alike the areas of digestive 
and of reproductive organs, and spreading itself with especial richness over the exclu- 
sively muscular part of the foot, which it will be recollected is the part of the animal 
most preeminently distended and distensible by both natural and artificial means. 
Lastly, in a large individual of the freshwater-mussel family in which a stiffening 
* Denksckriften der K. Akad. Wiss. Wien, viii. Bd. Taf. i. fig. 1 . 
