28 THE PHYSICAL BASIS OF LIFE 



seen, so minute as to pass tlirougli a fine filter, yet beyond 

 a doubt self -perpetuating and of specific type. The geneti- 

 cists continually ci'owd upon liini with fresh demonstra- 

 tions of those unseen somethings, aligned in orderly array 

 in the nuclear threads, each preserving its own specific 

 type amid all the shifting events of the nuclear life, w^itli- 

 out modification by its fellows, and somehow, generation 

 after generation, handing on its individual characteris- 

 tics to its descendants. 



With all this in mind the cytologist finds reason enough 

 to exercise his w^its upon the apparently structureless 

 ground-substance or hyaloplasm that seems to constitute 

 the fundamental basis of protoplasm and to be the source 

 of many of its formed elements. He can not resist the evi- 

 dence that the appearance of a simple, homogeneous col- 

 loidal substance that is offered by the hyaloplasm is de- 

 ceptive ; that it is in reality a complex, heterogeneous or 

 poly phasic system. He finds it difficult to escape the con- 

 clusion, therefore, that the visible and the invisible com- 

 ponents of the protoplasmic system differ only in their 

 size and degree of dispersion ; that they belong to a single, 

 continuous series ; and that the visible structure of proto- 

 plasm may thus give us something like a rough magnified 

 picture of the invisible. If so nmch be granted, the cytolo- 

 gist is led on to the conclusion that the ultra-microscopi- 

 cal dispersed particles of the hyaloplasm may be as highly 

 diversified chemically as are the visible formed bodies; 

 that they may be of all orders of magnitude ; and that it is 

 they which constitute the sources, or at least the forma- 

 tive foci, of those larger formed bodies that we have so 

 often, but erroneously, assumed to arise de novo. For my 

 part, I am disposed to take a final step by accepting the 

 probability that many of these particles (I do not say all) 

 as if they were ultra-microscopical plastids, may have a 



