In the Cosmaria, we find in each half of the animalcule (fig. 18. and 19.) a bladder in the axe (d.), and two other lateral ones (c. c.) of a darker colour, containing innumerable molecules, constantly turning and moving. I said above that the Cosmaria were to be considered as double animalcules, united during their whole life. In the Cosmarium deltoïdes (fig. 18—19.) I have seen both halves of the animalcule, separated during whole days, and two bladders, perfectly transparent and colourless, unloading in one another, and developing themselves. The bladders, where the contact took place, were visibly perforated. Soon after the developement of these bladders, I have seen the mass of the dark molecules of the bladder (d.) evacuated into the transparent one, in consequence of which a double stream of molecules (fig. 19. a. and b.) took place, crossing itself in the common opening, so that the molecules of the one ran into the bladder of the other animalcule, or part of it.
The Cosmarium bipes (fig. 20.) offers another instance of this exchange of a molecular fluid. We see here several animalcules under the form of a chain, united by obtuse points. Soon after this union, two other united animalcules open themselves by a long fissure (f.), and we see two streams of free molecules (fig. 20. a. g.) moving in the direction indicated by arrows, and operating in this manner the exchange of fluids.
