Pflanzen aus Zellen, deren selbstandiges Leben unmittelbar nachweisen lasst.Da nun alle Zellen nach denselben Gesetzen wachsen, also nicht in einem Falle der Grund des Wachstum in der Zelle selbst, im andern Falle im ganzen Organismus liegen kann, da sich ferner nachweisen lasst, dass einzelne, von den iibrigen in der Art des Wachstums nicht verschiedene Zellen selbstandig sich entwickeln, so miissen wir iiberhaupt den Zellen ein selbstandiges Leben zuschreiben. . . . Dass nicht wirklich jede einzelne Zelle, wenn sie von einem Organismus getrennt wird, weiter wachst, ist gegen diese Theorie so wenig ein Einwurf, als es ein Einwurf gegen das selbstandige Leben einer Biene ist, wenn sie getrennt von ihrem Schwarm auf die Dauer nicht fortbestehen kann." "One can thus construct the following two hypotheses concerning the origin of organic phenomena such as growth : either this origin is a function of the organism as a whole, or growth does not take place by means of any force residing in the entire organism but each elementary part possesses an individual force, a separate life."We have seen that all organisms consist of essentially like parts, the cells ; that these cells are formed and grow according to essentially the same laws ; that these processes are thus everywhere the result of the same forces. If, therefore, we find that some of these elementary parts, which do not differ from others, are capable of being separated from the organism and of continuing to grow independently, we can conclude that each of the other elementary parts, each cell, must possess the capacity to gather new molecules to itself and to grow, that therefore each cell possesses a particular force, an independent life, as a result of which it too would be capable of developing independently if only there be provided the external conditions under which it exists in the organism. The eggs of animals are in fact such cells, capable of living separated from the organism. Among the lower plants any cell can be separated from the plant and continue to grow. Thus, entire plants may consist of cells whose capacity for independent life can be clearly demonstrated. Now, since all cells grow according to the same laws so that it is not possible that in one case the cause of growth lies in the cell itself while in another case it lies in the entire organism, and since moreover it can be demonstrated that single cells whose growth does not differ from that of other cells can develop independently, we must therefore ascribe an independent life to the cell as such. That not every cell, when separated from the organism does in fact grow is no more an argument against this theory than is the fact that a bee soon dies when separated from its swarm, a valid argument against the individual life of the bee."
