JULY— SEPT. 1857.] between the Animal and Plant, 177
mine move closely the consanguinity of the two kingdoms, beginning Nvith the birth of the members of both in a simple cell, and then con- sidering what important parts cellular structures play throughout all the economy of their future life. Buffon on beholding the smallest animal of the existence of which we are aware, the little monad that swarms in stagnant water, ynagined that all vegetable and animals were built up of these minute cells. True to its unchanging philosophy, which laughs at every new truth, the world sneered at Buffon's impro- bcible idea ; but we know n*w that the sage naturalist saw truth in his dreams. Tl^e smallest of the Infusoria, the most minute Cryp- togam are but simple cells living an independent isolated life, and every living structure however complex, however strange, has had a cellular origin, and is indebted for its growth and maintenance to the modification and development of cells.[1] The cell consists of an enveloping membrane or cell wall, that encloses a peculiar fluid and nucleus or cell-germ. True we find numerous examples of ceils that do not exhibit even the trace of a nucleus, but from these it may either have been removed by absorption, or it may be destin- ed to appear at some future era of their existence. The modes of Cylogenesis are various, but nearly all agree in being common to the animal and vegetable. To the older Physiologists the subject of reproduction was fertile in speculation and romance, and it was only wh^n the theory of cells and their development became known, that we were able to read its history in the earlier and more myste- rious stages. In the higher animals and plants, the process is com- plicated in accordance with the general plan of organization, but as we approach the simple infusorial animal or cryptogamic plant, w^e can with facility explore the plan of nature's grand secret. Here new generations originate in accordance with the laws of Cytoge- nesis, the nucleus of the parent preparing a future race, or some of the other systems obtaining by which the old cell begets the new.
Remembering then that Cytogenesis is in all cases the necessary part of the process of reproduction, if from the generation of the lower species we proceed upwards to the more perfect animal or plant, we shall find that any complication of plan is merely sup-
- ↑ * Th« exceptions t-^ this general rul$ do not demand special notice.
