and Oviducal System in the LamellibrancMate Mollusks. 457 



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 allowing 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 dis- 

 placed than the stiffening size injection. 

 Thirdly, of triple injections. 



The readiness with which injections pass from the arterial into 

 the venous system make the triple injections 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 giving 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 be- 

 fore 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 exclusively 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 or other injection has been thrown in by 

 the orifice through which the generative products are extruded, 

 a simple lens is sufficient to show that the tubes thus injected 

 have the generative caeca affixed to them laterally, and pass on 

 continuously into parts of the foot in which no generative caeca 

 are lodged. It is most especially in that part of the muscular 

 foot into which no viscera are packed, and which forms a belt of 

 considerable width beyond and bounding the generative mass, 

 * Denkscbriften der K. Akad. Wiss. Wien, Bd. viii. Taf. i. fig. 1. 



