134 



THE CELL AND PROTOPLASM 



tinguishable from ordinary living organ- 

 isms. Laidlaw has presented a similar 

 view and has assembled much evidence in 

 its support. Doerr has just published a 

 masterly discussion of the nature of viruses 

 and bacteriophages in which he has pre- 

 sented and evaluated the ideas held by 

 different workers. He points out that the 

 large viruses are similar to the small vi- 

 ruses in all important respects, that there 

 is no reason for attempting to separate 

 them on the basis of size, and that, further- 

 more, no fundamental difference between 

 viruses and living organisms has been 

 demonstrated. In Doerr 's opinion, the 

 chief point of issue is whether non-living 

 infectious agents should be accepted along 

 with living infectious entities, or the smal- 

 lest virus accepted as a living agent, and af- 

 ter a thorough discussion he tends to resolve 

 the conflict in favor of the acceptance of 

 viruses as living even though they may 

 consist of a protein molecule. The path- 

 ologist has been able to rationalize his 

 knowledge of viruses with his knowledge 

 of living organisms so that he is willing to 

 accept the smallest virus, even though a 

 large nucleoprotein molecule, and the larg- 

 est living organism, as representatives of a 

 common series in which there is a definite 

 but almost imperceptible gradation of sub- 

 stance and of complexity of function. 



We come, therefore, to the interesting 

 situation where the pathologist and the 

 chemist have a common meeting ground, a 

 territory never before accessible with cer- 

 tainty. Needham has argued the necessity 

 of a bridge between morphology and bio- 

 chemistry, and the essence of this bridge 

 now appears to have been achieved between 

 pathology and chemistry. The chemist, 

 always interested in atoms and molecules, 

 has recently extended his knowledge in 

 two directions. At one extreme, nuclear 

 chemistry has achieved the transmutation 

 of elements and at the present time is 

 pushing vigorously ahead with studies on 

 the manner in which the protons and elec- 

 trons that make up the atoms are arranged 

 and on ways and means of breaking up 

 large and complex structures into simpler 



ones. Instead of being homogeneous, the 

 atoms appear to consist of a virtual maze 

 of discontinuities, but are nevertheless in 

 perfect order, as shown by the formation 

 of a barium atom during the disintegra- 

 tion of a large uranium atom. At the 

 other extreme, the chemist has found the 

 virus proteins, molecules larger than those 

 ever known before. However, the chemist 

 realizes that just as the chemical, biologi- 

 cal, and physical properties of ordinary 

 molecules are a direct result of their struc- 

 ture, so too must the properties of atoms 

 and of the viruses be a direct result of 

 their structure. This structure, whether 

 evidenced by the proton and electron of 

 the hydrogen atom, by the atoms of the 

 water molecule, or by the units combined 

 to make up a virus, must be fundamentally 

 the same. The recognition of the essential 

 identity of the structure of entities, regard- 

 less of their nature, that is, of structure 

 as a continuum from smallest to largest, 

 is of fundamental importance. Although 

 recognizing the significance and importance 

 of structure, many have been led astray 

 because of attempts to separate the living 

 from the non-living on the basis of certain 

 characteristics, not realizing that, as has 

 been stated many times before, the word 

 **life" is merely a definition of degree. 

 Attempts to arrive at a definite line of 

 division have resulted in failure in the 

 past and appear doomed to a similar fate 

 in the future. Fortunately, the classifica- 

 tion of an entity as living or non-living, 

 or as a cell or a molecule, is of little or no 

 importance, whereas the complete realiza- 

 tion of the expression inherent in structure 

 is of tremendous importance. 



I expressed the view two years ago that 

 from the standpoint of structure there is 

 no reason why a single structural entity, 

 which we call a molecule, should not be 

 larger than the ordered group of structural 

 entities which we call a cell. The over- 

 lapping of structure in the case of atoms is 

 well known, and the recent demonstration 

 of the formation of barium and other atoms 

 from a single uranium atom brings it even 

 more forcibly to attention. A similar situ- 



