In its plasmodial state, as has been said, the slime-mould affects damp or moist situations, and during warm weather in such places spreads over all moist surfaces, creeps through the interstices of the rotting bark, spreads between the cells, between the growth-layers of the wood, runs in corded vein-like nets between the wood and bark, and finds in all these cases nutrition in the products of organic decomposition. Such a plasmodium may be divided, and so long as suitable surroundings are maintained, each part will manifest all the properties of the whole. Parts of the same plasmodium will even coalesce again. If a piece of plasmodium-bearing wood be brought indoors, be protected from desiccation by aid of a moist dark chamber, not too warm (70 deg. F.), the organism seems to suffer little if any injury, but will continue for days or weeks to manifest all the phenomena of living matter. Thus, under such circumstances, the plasmodium will constantly change shape and position, can be induced to spread over a plate of moist glass, and so be transferred to the stage of a microscope, there to exhibit in the richest and most interesting and abundant fashion the streaming protoplasmic currents. As just indicated, the plasmodia follow moisture, creep from one moist substance to another, especially follow nutritive substrata. They seem also to secure in some way exclusive possession. I have never seen them interfered with by hyphae or enemies of any sort, nor do they seem to interfere with one another. Plasmodia of two common species, _Hemitrichia clavata_ and _H. vesparium_ are often side by side on the same substratum, but do not mix, and their perfected fruits presently stand erect side by side, each with its own characteristics, entirely unaffected by the presence of the other. On the other hand, it is probable that some of the forms which, judged by their different fructifications, and by this alone, are to us distinct, may be more closely related than we suspect, and puzzling phases which show the distinctive marks supposed to characterize different species are no doubt sometimes to be explained on the theory of plasmodial crossing; they are hybrids.