THE NUTRITIVE ATTRACTIONS. 701 



the vascular parts, all the moist non-vascular tissues, such as the car- 

 tilages, the cornea, the capsule and the substance of the crystalline 

 lens, and, likewise, probably even reaches the intervals between the 

 cells of epithelial and epidermoid tissues. The essential difference 

 between a vascular and a non-vascular tissue, consists in the relative dis- 

 tance of their microscopic elements from the nearest capillary vessels, 

 and, therefore, in the space through which the plasma has to pass from 

 those vessels before it penetrates the tissue. All the tissues, indeed, 

 whether vascular or non-vascular, whether penetrated by capillaries or 

 not, are, strictly speaking, extra-vascular, that is to say, their elementary 

 parts are outside the walls of the corpuscles. The existence of serous 

 or white vessels smaller than, but continuous with, the capillaries, is 

 not generally admitted; but in certain tissues, secondary nutritive 

 channels may exist, as, for example the lacunae and canaliculi of bone, 

 and the tubuli of the dentine, by aid of which the nutritive fluid may 

 be still' further distributed. The tubular structure of the connective 

 tissue corpuscles and their processes, and the connection of these with 

 the lymphatics, are not admitted. 



The second stage of the nutritive process consists in the exercise of 

 a certain selective act, or so-called elective affinity, by the elementary 

 parts of the tissues and organs, by which they assimilate to themselves 

 such portions of the nutritive fluid as are suitable, either without or 

 with further change, to renew, molecule by molecule, their disinte- 

 grating substance. The nucleated cells of the epidermis and epithelium, 

 the corpuscles of the gray matter of the brain, the tubular fibres of 

 the white nervous tissues, the complex fibres of the striated muscles, 

 the simple fibrous forms of the contractile fibres or fibre-cells of the 

 organic muscular tissue, and of the fibrous and areolar tissues, and 

 lastly, the consolidated intercellular substance, with the remnants of 

 cells embedded in it, as in cartilage and bone, each derives from the 

 exuded plasma of the blood, and assimilates, its required chemical con- 

 stituents. The more rapid the waste, the more active is the renovation, 

 both processes being most marked in the muscular and nervous tissues, 

 which produce and regulate all animal movement. This assimilative 

 power of the tissue elements is the persistent, primitive, nutritive force, 

 inherited from the germ-cell. It is probably alike possessed by every 

 cell, however remote in its descent from the parent cell, and however 

 modified, so as to form parts of a composite animal or tissue, just as 

 it undoubtedly is when a single cell constitutes the entire animal. This 

 germ force, or germinal force, is the essential cause of all nutritive 

 phenomena, as it is of all organization, whether animal or vegetable. 

 By it, the cellular yeast plant grows and maintains itself in fermenting 

 saccharine solutions, the larger fungi feed themselves upon juices 

 derived from decaying organic matter in the soil, the various tissues 

 of the more complex flowering plants are formed and supported out of 

 a common pabulum, the sap ; and, in the Animal Kingdom, the uni- 

 cellular Gregarina, the sarcodous Rhizopod, the proteiform Amoeba, 

 the soft-bodied Coelenterata, with their ectoderm, endoderm, and in- 

 termediate tissue, and, lastly, all the complex tissues and various 

 organs of animals higher in the scale, and of Man, are duly nourished. 



