tions of structure in cells as the results of post mortem change or of fixing reagents. To such the living protoplasm is a homogeneous colloid, and its "peculiar and transcendental qualities are associated with molecular rather than with molar structure."
What is said as to the cell-contents applies also to the nucleus in which a reticular or meshwork appearance is described by some, as others would regard the actual living condition as one of perfect homogeneity.
In this uncertain state the question of the intimate structure of the living cell-protoplasm must at present be left, so far as the same is capable of investigation by the microscope and its accessories. But, whilst fully recognising that with further improvements in method and in means this problem will be solved, it none the less seems certain, consistently with the present hypotheses as to the nature of the cosmos, that however far the eye may be able to penetrate, there will still remain behind and beyond a molecular or atomic structure, for the understanding of which other branches of scientific enquiry must be employed. "The organism," says Virchow, "is not an individual but a social mechanism. An exact anatomical analysis of this mechanism always brings us at last to cells; they are the ultimate constituents of all tissues
