Thus, so far as outward form and the general character of the cycle of modifications, through which the organism passes in the course of its life, are concerned, the resemblance between _Chlamydomonas_ and _Heteromita_ is of the closest description. And on the face of the matter there is no ground for refusing to admit that _Heteromita_ may be related to _Chlamydomonas_, as the colourless fungus is to the green alga. _Volvox_ may be compared to a hollow sphere, the wall of which is made up of coherent Chlamydomonads; and which progresses with a rotating motion effected by the paddling of the multitudinous pairs of cilia which project from its surface. Each _Volvox_monad, moreover, possesses a red pigment spot, like the simplest form of eye known among animals. The methods of fissive multiplication and of conjugation observed in the monads of this locomotive globe are essentially similar to those observed in _Chlamydomonas_; and, though a hard battle has been fought over it, _Volvox_ is now finally surrendered to the Botanists. Thus there is really no reason why _Heteromita_ may not be a plant; and this conclusion would be very satisfactory, if it were not equally easy to show that there is really no reason why it should not be an animal. For there are numerous organisms presenting the closest resemblance to _Heteromita_, and, like it, grouped under the general name of “Monads,” which, nevertheless, can be observed to take in solid nutriment, and which, therefore, have a virtual, if not an actual, mouth and digestive cavity, and thus come under Cuvier’s definition of an animal. Numerous forms of such animals have been described by Ehrenberg, Dujardin, H. James Clark, and other writers on the _Infusoria_. Indeed, in another infusion of hay in which my _Heteromita lens_ occurred, there were innumerable infusorial animalcules belonging to the well-known species _Colpoda cucullus_.[35] Full-sized specimens of this animalcule attain a length of between 1/300 or 1/400 of an inch, so that it may have ten times the length and a thousand times the mass of a _Heteromita_. In shape, it is not altogether unlike _Heteromita_. The small end, however, is not produced into one long cilium, but the general surface of the body is covered with small actively vibrating ciliary organs, which are only longest at the small end. At the point which answers to that from which the two cilia arise in _Heteromita_, there is a conical depression, the mouth; and, in young specimens, a tapering filament, which reminds one of the posterior cilium of _Heteromita_, projects from this region.