by fission the Heteromita remains active; but sometimes another mode of fission occurs. The body becomes rounded and quiescent, or nearly so; and while in this resting state divides into two portions, each of which is rapidly converted into an active Heteromita.
A still more remarkable phenomenon is that kind of multiplication which is preceded by the union of two monads, by a process which is termed conjugation. Two active Heteromitæ become applied to one another, and then slowly and gradually coalesce into one body. The two nuclei run into one; and the mass resulting from the conjugation of the two Heteromitæ, thus fused together, has a triangular form. The two pairs of cilia are to be seen, for some time, at two of the angles, which answer to the small ends of the conjoined monads; but they ultimately vanish and the twin organism, in which all visible traces of organization have disappeared, falls into a state of rest. Sudden wave-like movements of its substance next occur: and, in a short time, the apices of the triangular mass burst, and give exit to a dense yellowish, glairy fluid filled with minute granules. This process, which, it will be observed, involves the actual confluence and mixture of the substance of two distinct organisms, is effected in the space of about two hours.
The authors whom I quote say that they "cannot express the excessive minuteness of the granules in question, and they estimate their diameter at less than .000005 of an inch. Under the highest powers of the microscope at present applicable such specks are hardly discernible. Nevertheless, particles of this size are massive when compared to physical molecules; whence there is no reason to doubt that each, small as it is, may have a molecular structure sufficiently complex to give rise to the phenomena of life. And, as a matter of fact, by patient watching of the place at which these infinitesimal living particles were discharged, our observers assured themselves of their growth and development into new monads. These, in about four hours from their being set free, had attained a sixth of the length of the parent, with the characteristic cilia, though at first they were quite motionless; and in four hours more they had attained the dimensions and exhibited all the activity of the adult. These inconceivably minute particles are therefore the germs of the Heteromita; and from the dimensions of these germs it is easily shown that the body formed by conjugagation may, at a low estimate, have given exit to thirty thousand of them; a result of a matrimonial process whereby the contracting parties, without a metaphor, "become one flesh," enough to make a Malthusian despair of the future of the universe.
I am not aware that the investigators from whom I have borrowed this history have endeavoured to ascertain whether their monads take solid nutriment or not; so that though they help us very much to fill up the blanks in the history of my Heteromita, their observations throw no light on the problem we are trying to solve — is it an animal or is it a plant?
Undoubtedly it is possible to bring forward very strong arguments in favour of regarding Heteromita as a plant.
For example, there is a fungus, an obscure and almost microscopic mould, termed Peronospora infestans. Like many other fungi, the Peronosporæ are parasitic upon other plants; and this particular Peronospora happens to have attained much notoriety and political importance, in a way not without a parallel in the career of notorious politicians, namely, by reason of the frightful mischief it has done to mankind. For it is this fungus which is the cause of the potato-disease; and, therefore Peronospora infestans (doubtless of exclusively Saxon origin, though not accurately known to be so) brought about the Irish famine. The plants afflicted with the malady are found to be infested by a mould, consisting of fine tubular filaments, termed hyphæ,
