the genetic relations of the several components of the organs, it served as a fresh starting point for the investigation of biological problems, since it was recognised that the life of the organism was but the life of the cell, differing only in degree of completeness; and the full realisation of what is meant by specialisation of function being dependent on differentiation of structure became apparent.
With entire appreciation of the complexity of the phenomena presented by the living cell, Brücke forty years ago affirmed that this must imply the existence of some structural arrangement in the cell substance, some degree of organisation, some further stage than had hitherto been detected in the disposition of the material which subserves function. Setting aside the obvious distinction into cell-contents nucleus and attraction-sphere, and the separation of the first into cell-protoplasm and the metabolic products thereof (such as starch, fat, glycogen and pigment granules), attention has been directed towards discovering in the apparently homogeneous protoplasm some evidence of structure. Numerous observers long ago described a fibrillar arrangement in this material, a view that later gave place to the assertion that it is rather to be regarded as of a reticular nature, the protoplasm forming a network or meshwork "the nodal
