[8] Or offcasts from pre-existing fungi,--constituting the “micrococci” of Professor Hallier. 3. ORIGIN OF BACTERIA AND OF TORULÆ BY ARCHEBIOSIS. The evidence on this part of the subject is, I think, sharply defined and conclusive. Simple experiments can be had recourse to, which are not admissible in the discussion of the question as to the origin of _Bacteria_ and _Torulæ_ by Heterogenesis. There, we wish to establish the fact that living matter is capable of undergoing a certain metamorphosis, and consequently, we must deal with living matter. Here, however, with the view of establishing the fact that living matter can arise _de novo_, if we are able, shortly after beginning our experiment, to arrive at a reasonable and well-based assurance that no living thing exists in the hermetically sealed experimental vessel--if the measures that we have adopted fully entitle us to believe that all living things which may have pre-existed therein have been killed--we may feel pretty sure that any living organisms which are subsequently found, when the vessel is broken, must have originated from some re-arrangements which had taken place amongst the not-living constituents of the experimental solutions, whereby life-initiating combinations had been formed. The possibility of the _de novo_ origination of _Bacteria_, _Torulæ_, and other such organisms, is one which is intimately associated with the doctrine as to the cause of fermentation and putrefaction. With regard to the almost invariable association of such organisms with some of these processes, almost all are agreed. There is, moreover, a very frequent association of particular kinds of organisms with particular kinds of fermentation. Hence the assumption is an easy and a natural one to many persons, that the organisms which are invariably met with in some cases are the causes of these fermentations,[9] although it is quite obvious that the facts on which this view is based, are equally explicable on the supposition that the organisms are concomitant results or products (due to new chemical combinations) of the fermentative changes. In the one case the fermentative changes are believed to be initiated by the influence of living organisms; and those who regard living things as the only true _ferments_, for the most part also believe that living things are incapable of arising _de novo_. They think that those organisms which serve to initiate the changes in question, have been derived from a multitudinous army of omnipresent atmospheric germs, which are always ready, in number and kind suitable for every emergency. This is the doctrine of M. Pasteur and others. On the other hand, fermentations and putrefactions may be regarded as sets of chemical changes, which are apt to occur in organic and other complex substances--these changes being due either to the intrinsic instability of the body which manifests them, or to molecular movements communicated to it by a still more unstable body.