Prefc 



ace 



THE SUBJECT of this year's Symposium ot the Society of General Physiologists, 

 'Subcellular Particles,' was selected by the Council of the Society. In the 

 organization of this symposium, the aim was two-fold: first, to bring to the 

 attention of the variegated membership of the Society the most recent work of 

 the foremost in\estigators studying subcellular particles; and second, to emphasize 

 the structural aspects of subcellular particles as related to their function, especially 

 with regard to the properties of the heterogeneous system created by the very 

 presence of the particulate material within the cell. It would be presumptuous 

 to say that these aims were achieved with any degree of success, especially in the 

 case of the second part of the over-all aim, where a large area of ignorance faces 

 the experimenter. 



The post-war years will, I believe, be considered a '(jolden Era" in the biological 

 sciences and certainly in the study of cell inclusions. Tremendous advances have 

 been made in elucidating the various activities of subcellular structures, due 

 primarily to advances in technology and the inspiration of new concepts and new 

 information from allied fields, as microbiology. Thus improvements in, and the 

 coordination of, techniques in ultracentrifugation, electron microscopy and micro- 

 chemical analysis have made possible a more definitive correlation between the 

 particles or the parts thereof and their activities within the cell. Likewise, new 

 information about important biochemical substances, as the nucleic acids, have 

 influenced the trend of thought as to the function of intracellular structures. Yet, 

 essentially, this type of progress of knowledge in this field does not shed light on 

 such questions as /) why are structural units necessary at all, and 2) what 

 efTect does structure have on chemical or biochemical conditions and/or reactions 

 within the cell ? 



Howe\er, certain consistent generalities can be observed as the result of the 

 sharp attention paid to intracellular structures. For example, structures seem to 

 be involved in those situations where the cell requires protection from disrupting 

 agents which, nonetheless, the cell must include as a part of its over-all organi- 

 zation in order to maintain a specialized function. Thus enzymes which, if 

 allowed loose in the cell, would cause autolysis would be included in this category. 

 Several papers in this volume point to this aspect of cellular structure and function. 



Structure also seems to be necessary in the general situation where synthesis ot 

 substances is taking place. Here, however, in spite ot the speculations concerning 

 'templates' the situation is not so simple nor so clear that the conclusion can be 

 stated with any finality. A third and what seems to be a most important require- 

 ment for structure within the clII is lound in the case of cellular activities resulting 



vii 



