44 The Structure of Protoplasyn 



level, the whole cell at mitosis becomes a single mechanism, ephem- 

 eral, yes, but a mechanism nevertheless, for a specific purpose, and 

 for a short time the particles of the cell may be considered also as 

 having lost their identity. 



We must interpolate here, before taking up any of the specific 

 molecular characteristics, two points of view which are constantly 

 creeping into our ways of thinking of protoplasm; one is analytic in 

 nature; the other, synthetic. These terms are rather loosely descrip- 

 tive, but differences will appear as we proceed. 



To understand a mechanism in protoplasm, we must first recog- 

 nize that it is a mechanism; and when we have broken it down to 

 its components, we must also, by some experimental means, recog- 

 nize the components as such. Thus we may step from the level of a 

 living structural mechanism, which we have recognized by physio- 

 logical experimentation, down to the level of the components, which 

 we study by physical-chemical methods. We assume that the 

 physiological processes by which we recognized the mechanism 

 have their origin in the physical or chemical characteristics of some 

 portions of the component pieces into which the mechanism has 

 been broken. In this analytic method we seek these active portions 

 and are likely to disregard the original framework. Opposed to this 

 analytic procedure the synthetic method starts with atoms and 

 molecules as building stones for the construction of larger particles 

 and mechanisms. Each step up is possible only because the charac- 

 teristic properties of the small structural building stones make 

 specific spatial arrangements possible. This building-up process 

 presupposes a knowledge of certain properties of the components 

 which will allow them to take up specific positions with respect to 

 one another, and as a result of their relative positions, willy nilly, 

 to form mechanisms essential to the activity of the cell. The analytic 

 method starts with a rather vague mechanism, known principally 

 by its performances, and attempts to comprehend the machine by 

 breaking it down and observing the behavior of the pieces which in 

 turn are not too well comprehended. In contrast to this the syn- 

 thetic method dwells more on the structure of the fairly well known 

 components but understands the behavior less when the components 

 are assembled. Obviously both methods are essential to a reason- 

 ably clear understanding of vital activities, but it is the latter method 

 which is of especial interest to us here. Of course, in any study, 

 these two procedures are often used interchangeably, and along 



