PROBLEMS AND MATERIAL " 5 



is also often convenient to conceive the direction in which these orders 

 appear as representing a physiological axis and to designate developmen- 

 tal pattern in which serial orders of this sort occur as axiate pattern. Not 

 only the whole organism but its various parts, appendages, many organs, 

 or even individual cells may develop axiate pattern, and the axes of such 

 patterns may be in all possible directions within the same organism. 



The features of axiate pattern which first become evident in develop- 

 ment are polarity and symmetry or asymmetry of the whole. These seem 

 to constitute a sort of background in relation to which the further de- 

 velopment of pattern takes place. They may be compared to a system of 

 co-ordinates, a frame of reference, with respect to which each part has a 

 definite position. This analogy, however, must not be pushed too far, for 

 observation of the course of development indicates, and experimental 

 analysis demonstrates, that the factors which constitute this apparent 

 frame of reference are not merely formal in character but are physiologi- 

 cally operative in localization and determination of the course of develop- 

 ment and that their action can be altered or they can be obliterated experi- 

 mentally by change in physiological condition of the protoplasm con- 

 cerned. They apparently constitute wholeness in its simplest, most gen- 

 eral terms. They appear to be the primary organizing and also the pri- 

 mary integrating factors. 



Polarities, symmetries, and asymmetries of one kind or another appear 

 in many nonliving systems. In crystals, for example, we find one sort of 

 polarity and symmetry; in flames, flowing streams, electric currents, etc., 

 polarities of other kinds. Many biologists have attempted to interpret 

 axiate pattern in organisms in terms of protoplasmic molecular or micellar 

 orientation, symmetry, or asymmetry similar or analogous to that of the 

 crystal or other physical systems. While such molecular or micellar struc- 

 tures are unquestionably present in fibrillae, membranes, skeletal and 

 cuticular structures, shells, and various colloid particles, often constituting 

 local structural patterns, there is at present no evidence that they de- 

 termine the general order and pattern of the whole organism, and there is 

 considerable evidence that organismic pattern is quite different in char- 

 acter. These molecular and micellar patterns are apparently chiefly char- 

 acteristic of differentiated protoplasms of certain tissues and of nonliving 

 products of metabolism and of secondary and local significance in develop- 

 ment. They occur in all possible orientations with respect to the axes of 

 organisms and even of organs in which they develop. They appear to be 

 eft'ects or expressions of pattern rather than its primary framework. 



