This is but another mode of stating the same thing as above referred to by M. Trécul, that certain cells, resembling yeast cells (_Torula_), are developed spontaneously, and that these ultimately pass through the form of mould called _Penicillium_ to the more complex _Mucor_ (which the writer evidently has confounded with _Aspergillus_, unless he alludes to the ascigerous form of _Aspergillus_, long known as _Eurotium_). From what is now known of the polymorphism of fungi, there would be little difficulty in believing that cells resembling yeast cells would develop into _Penicillium_, as they do in _fact_ in what is called the "vinegar plant," and that the capsuliferous, or higher condition of this mould may be a _Mucor_, in which the sporules are produced in capsules. The difficulty arises earlier, in the supposed spontaneous origination of yeast cells from molecules, which result from the peculiar conditions of light, temperature, &c., in which certain solutions are placed. It would be impossible to review all the arguments, or tabulate all the experiments, which have been employed for and against this theory. It could not be passed over in silence, since it has been one of the stirring questions of the day. The great problem how to exclude all germs from the solutions experimented upon, and to keep them excluded, lies at the foundation of the theory. It must ever, as we think, be matter of doubt that all germs were not excluded or destroyed, rather than one of belief that forms known to be developed day by day from germs should under other conditions originate spontaneously.