In the early days of the cell-theory, more than seventy years ago, Goodsir was wont to speak of cells as ãcentres of growthã or ãcentres of nutrition,ã and to consider them as essentially ãcentres of force.ã He looked forward to a time when the forces connected with the cell should be particularly investigated: when, that is to say, minute anatomy should be studied in its dynamical aspect. ãWhen this branch of enquiry,ã he says ãshall have been opened up, we shall expect to have a science of organic forces, having direct relation to anatomy, the science of organic forms1.ã And likewise, long afterwards, Giard contemplated a science of morphodynamique,ãbut still looked upon it as forming so guarded and hidden a ãterritoire scientifique, que la plupart des naturalistes de nos jours ne le verront que comme Moû₤se vit la terre promise, seulement de loin et sans pouvoir y entrer2.ã
To the external forms of cells, and to the forces which produce and modify these forms, we shall pay attention in a later chapter. But there are forms and conôÙfiôÙgurôÙaôÙtions of matter within the cell, which also deserve to be studied with due regard to the forces, known or unknown, of whose resultant they are the visible expression.
In the long interval since Goodsirãs day, the visible structure, the conformation and configuration, of the cell, has been studied far more abundantly than the purely dynamic problems that are associated therewith. The overwhelming progress of microscopic observation has multiplied our knowledge of cellular and intracellular structure; and to the multitude of visible structures it {157} has been often easier to attribute virtues than to ascribe intelligible functions or modes of action. But here and there nevertheless, throughout the whole literature of the subject, we find recognition of the inevitable fact that dynamical problems lie behind the morphological problems of the cell.
Bû¥tschli pointed out forty years ago, with emphatic clearness, the failure of morphological methods, and the need for physical methods, if we were to penetrate deeper into the essential nature of the cell3. And such men as Loeb and Whitman, Driesch and Roux, and not a few besides, have pursued the same train of thought and similar methods of enquiry.
Whitman4, for instance, puts the case in a nutshell when, in speaking of the so-called ãcaryokineticã phenomena of nuclear division, he reminds us that the leading idea in the term ãcaryokinesisã is motion,ããmotion viewed as an exponent of forces residing in, or acting upon, the nucleus. It regards the nucleus as a seat of energy, which displays itself in phenomena of motion5.ã
In short it would seem evident that, except in relation to a dynamical inôÙvesôÙtiôÙgaôÙtion, the mere study of cell structure has but little value of its own. That a given cell, an ovum for instance, contains this or that visible substance or structure, germinal vesicle or germinal spot, chromatin or achromatin, chromosomes or centrosomes, obviously gives no explanation of the activities of the cell. And in all such hypotheses as that of ãpangenesis,ã in all the theories which attribute specific properties to micellae, {158} idioplasts, ids, or other constituent particles of protoplasm or of the cell, we are apt to fall into the