MOLECULAR STRUCTURE IN PROTOPLASM 



167 



tures. These three things, materials, activi- 

 ties, and versatility, if we may so speak of 

 them, are the basic concepts towards which 

 we must proceed if a comprehension of 

 vital phenomena is to be attained. How to 

 proceed towards attainment of such an 

 understanding has been a question for the 

 past 100 years, and in our clumsy, human 

 way we have been slowly enlarging our 

 comprehension principally by reducing a 

 chaotic world to a more simplified picture, 

 one which seems to come within our reach. 

 Our task here is primarily with the mate- 

 rials, the structure only. 



The discovery that all organisms are con- 

 structed of cells was a great leveling and 

 simplifying conception. The further dis- 

 covery that the slimy cell content is the 

 physical basis for life was again a simplify- 

 ing step ; and when analyses showed us that 

 this material was composed of only a few 

 different chemical elements and that these 

 were the same with only slight exceptions 

 for all living organisms, the hundreds of 

 thousands of species of organisms which 

 formed our vital, chaotic world took on 

 another relatively simple, comprehensible 

 aspect from the point of view of materials 

 involved in construction. From the point 

 of view of activity (within this mass of only 

 a few elements), a great simplifying discov- 

 ery, to mention only one simple example, 

 was that CO2 is a product of respiration 

 which is common to all organisms. We are 

 still left, however, with the problem of ver- 

 satility. The elephant, the humming bird, 

 the angle worm, the protozoan, the liver- 

 wort, and the redwood tree all fit in with 

 the simplifying concepts of cell structure, 

 of protoplasm, and of respiration; but the 

 elephant certainly has a different outlook 

 upon life than the humming bird, at least 

 as far as locomotion is concerned ; what the 

 protozoan, the angle worm, and the red- 

 wood tree may think about surrounding 

 conditions and the state of society certainly 

 would not be likely to confirm the opinions 

 of the elephant and the humming bird. 

 Yet all of these derive their opinions from 

 the same few elements, bound up in the 

 same sort of slimy protoplasm, enclosed in 

 the same sort of cells. 



Still another common denominator is be- 

 ing recognized in the submicroscopic and 

 molecular range of sizes. This has been 

 slowly taking shape during the past two or 

 three decades and has been accelerating 

 considerably during the present decade. 

 This common denominator is the molecular 

 structural aspect of protoplasm. From this 

 molecular viewpoint the picture is still 

 foggy, as might be expected at this stage, 

 but through the fog certain general out- 

 lines of structure are appearing which give 

 hints of occasional detail. In our attempts 

 to penetrate this fog we shall undoubtedly 

 misinterpret the form which we think we 

 see, but that is to be expected also and may 

 even be beneficial as an incentive to a 

 further clarification of the picture. 



The general conception of structure, I 

 presume, is as old with the human race as 

 the ability to form thoughts; and during 

 the ages it has been promptly extended in 

 both directions when new tools were in- 

 vented, by the telescope in one direction, 

 and by the miscroscope in the other. Even 

 before the tools were made available, 

 imagination had invented the atom as the 

 structural unit of all substances; but it 

 was not until the tools were made and 

 methods of thought developed that very 

 much credence was placed in the theories 

 of the structure of matter. 



In the organic world theories of struc- 

 ture have passed through various stages or 

 levels in the size of the structural units. 

 The recognition of similarities between 

 whole organisms brought great simplicity 

 into the notion of a living world and 

 brought into existence our taxonomic struc- 

 ture. The invention of the microscope 

 must have produced a chaotic first impres- 

 sion, to be dispelled only when its extensive 

 use resulted in the simplifying theory 

 accredited to Schleiden and Schwann that 

 cells are the structural building units of 

 all organisms. 



About this time a further simplifying no- 

 tion was propounded — that the slimy mate- 

 rial in the cells forms the physical basis of 

 living material; and I presume that this 

 was immediately followed by the unifying 

 idea that this material is common to all 



