Let us illustrate by the example of the formation of a crystal out of a simple solution. A nucleus first appears, then increment after increment is added, according to laws, until the crystal is formed. The case of the origin of a Monad is a parallel one. We have a solution; in this solution appears the Monad. There is no more necessity for the pre-existence of a Monad in the solution than that there should have been a pre-existing parent crystal. In both solutions exist the elements of which the Monad and Crystal are formed; the laws according to which they are formed are as susceptible of study in the one case as in the other. Theoretically, therefore, there is no objection to the idea of Spontaneous Generation, the laws of which must be investigated as any other mechanical problem has been; the problem being a question of the redistribution of matter. In fact, according to the experiments of Pouchet, Pennetier, Bastian, Wyman, and others. Vibrios and Bacteria do appear in solutions where there was not previously a trace of these minute beings.
Want of space prevents us from discussing this question in detail. We can only say that at present the evidence seems to us in favor of the view that Spontaneous Generation takes place at the present day under favorable conditions. We turn now to the consideration of living Monera and Amœbae. Whatever their present or remote origin may have been, an Amoeba is a Monas with a nucleus. The Amoebae probably came originally from Monera, if they are not now so produced, and in some cases colonize themselves, forming the Sponge,—this view being suggested by the young of the Sponges, which cannot be distinguished from Amoebae,—or the Amoebae gaining tails and hairs, like the Euglena, gave rise to the Animalcula or Infusoria. But as certain Amoebae and Euglena cannot be distinguished from the spores or young of the simplest plants, the origin of the vegetal world must be sought also in these minute beings. If, now, Spontaneous Generation does not take place, the Monera and Amoebae of the present day, and the other orders of the Intermediate Kingdom also, are the posterity of the long dead original forms, the ancestors of the three kingdoms,—the animal, the vegetal, and the intermediate world. (See Tree I., page 24.)
