It is true that in some three or four instances of this saprophytic destruction of organic tissues, I have observed that, after the strong bacterial investment, there has arisen, not the two forms just named, nor either of them, but one or other of the striking forms now called _Tetramitus rostratus_ and _Polytoma uvella_; but this has been in relatively few instances. The rule is that _Cercomonas typica_ or its congener precedes other forms, that not only succeed them in promoting and carrying to a still further point the putrescence of the fermenting substance, but appear to be aided in the accomplishment of this by mechanical means. By this time the mass of tissue has ceased to cohere. The mass has largely disintegrated, and there appears among the countless bacterial and monad forms some one, and sometimes even three forms, that while they at first swim and gyrate, and glide about the decomposing matter, which is now much less closely invested by _Cercomonas typica_, or those organisms that may have acted in its place, they also resort to an entirely new mode of movement. One of these forms is _Heteromita rostrata_, which, it will be remembered, in addition to a front flagellum, has also a long fiber or flagellum-like appendage that gracefully trails as it swims. At certain periods of its life they anchor themselves in countless billions all over the fermenting tissues, and as I have described in the life history of this form, they coil their anchored fiber, as does a vorticellan, bringing the body to the level of the point of anchorage, then shoot out the body with lightning-like rapidity, and bring it down like a hammer on some point of the decomposition. It rests here for a second or two, and repeats the process; and this is taking place by what seems almost like rhythmic movement all over the rotting tissue. The results are scarcely visible in the mass. But if a group of these organisms be watched, attached to a small particle of the fermenting tissue, it will be seen to gradually diminish, and at length to disappear. Now, there are at least two other similar forms, one of which, _Heteromita uncinata_, is similar in action, and the other of which, _Dallingeria drysdali_, is much more powerful, being possessed of a double anchor, and springing down upon the decadent mass with relatively far greater power. Now, it is under the action of these last forms that in a period varying from one month to two or three the entire substance of the organic tissues disappears, and the decomposition has been designated by me "exhausted"; nothing being left in the vessel but slightly noxious and pale gray water, charged with carbonic acid, and a fine, buff colored, impalpable sediment at the bottom.