FOREWORD 



This volume on The Cell and Protoplasm 

 is the tenth symposium published by the 

 American Association for the Advance- 

 ment of Science in the three years that have 

 elapsed since it began such publications in 

 1938. Like the earlier volumes in this series, 

 this one is a systematic and authoritative 

 treatment by eminent specialists of an im- 

 portant field of science. 



In a sense the Cell Theory is not new, for 

 the long history of its development in- 

 cludes dim foreshadowings by Greek nat- 

 uralists of Aristotle's time and approaches 

 to it by Robert Hooke in 1665, nearly two 

 centuries in advance of the important 

 papers of Schleiden and Schwann, in com- 

 memoration of the centennial of which this 

 symposium was organized. In another sense 

 the Cell Theory is always new, for every 

 discovery respecting this primary and es- 

 sential unit of living organisms, both plant 

 and animal, has raised more questions than 

 it has answered and has always widened 

 the fields of inquiry. 



The fact that there are many possible 

 approaches to an understanding of the 

 nature of the living cell is indicated by the 

 variety of chief scientific interests of the 

 seventeen contributors to this symposium. 

 In biographical directories five of them are 

 classed as zoologists, four as chemists, three 

 as botanists, two as anatomists, and one 

 each as a biologist, a geneticist and a bio- 

 chemist. Specialists in seven fairly dis- 

 tinct branches of science have participated 

 in a survey of what has been established 

 regarding living cells and protoplasm, often 

 indicating what is only probable or con- 

 jectural and sometimes pointing out what 

 is quite unknown. 



From the Table of Contents it will be 

 found that this volume contains discussions 

 of such various biological entities as cell 

 walls, chromosomes, genes, viruses, en- 

 zymes, hormones and vitamins; and of 

 such various questions of mutual relation- 

 ships as nucleus and cytoplasm, chromo- 

 somes and genes, cell differentiation and 

 external environment, cell differentiation 

 and internal environment, and the cell and 

 the organism. It will be found that there 

 are reports on such various basic investiga- 

 tions as the bridge between the living and 



the lifeless, the biochemistry of micro-organ- 

 isms, the physical and chemical properties 

 of protoplasm and colloids, and the nature 

 and mode of action of structural units in 

 cellular physiology. Finally, illustrations 

 will be found of the use of such technical 

 means as the compound microscope and a 

 discussion of the micromanipulation of 

 living cells. 



Previous symposia published by the As- 

 sociation were presented at its meetings. 

 This one was held during five days imme- 

 diately following the meeting of the Pacific 

 Division at Stanford University in June, 

 1939. It was not, however, local in its or- 

 ganization nor participated in only by local 

 scientists. Of the seventeen contributors, 

 seven were from the Pacific Slope, one from 

 the Middle West, six from the East and 

 three from Europe. Thus to the variety of 

 chief interests of the participants is added 

 the wide diversity of their environment 

 and immediate scientific associations. 



It would be difficult to name a more im- 

 portant and interesting subject for a joint 

 discussion by biologists, biochemists and 

 chemists than that treated in this sympo- 

 sium, for protoplasm is the material basis 

 of life and the cell is the fundamental 

 unit involved in the vital processes of all 

 the myriads of kinds of living organisms 

 that inhabit the earth. The fact that this 

 unit is common not only to all species 

 of plants and animals but also to all their 

 parts enormously multiplies the opportuni- 

 ties for investigating its properties and the 

 modes of its functioning. Its universal 

 presence implies its importance in all prob- 

 lems of growth, maturity and senescence, 

 of health and disease, of heredity and vari- 

 ation. 



As its name indicates, the primary pur- 

 pose of the Association is to contribute to 

 the advancement of science. It is fulfilling 

 this purpose in various ways, one of which 

 is by publishing the best of the symposia 

 that are presented at its meetings. In mak- 

 ing available in this volume a clear, com- 

 prehensive and documented summary of 

 what is now known concerning living cells 

 and protoplasm the Association makes a 

 substantial contribution to progress in 

 biology. F. R. Moulton 



