wise stated : the utmost degree of organic evolution can 

 be attained by the triaxial method of growth, and by 

 no other ; or, triaxial growth is the only way in which 

 maximum organic development is possible. 



But constructive Tightness must have its external as 

 well as internal aspect. That is, any architectural 

 plan, to have superior constructive value, must con- 

 form in a superior way to the influences of the outer 

 world from which all its constructive supplies are 

 drawn. 



The triaxial system fulfils both these basic require- 

 ments: (i) In its unequalled power of growth and 

 progressive internal organization; (2) In that, archi- 

 tecturally and functionally, it is the only system which 

 can be oriented in a profitable way, on the one hand, 

 to the more constant, and on the other, to the more vari- 

 able lines of gradient action in the outer world. Ulti- 

 mately it does become so oriented. 



More specifically, this architectural Tightness is 

 manifest: (i) In the coincidence of the axis of locomo- 

 tion with the main axis of growth, and with the three 

 longitudinal trunk lines of organic conveyance, nerv- 

 ous, alimentary, and vascular. (2) In the location of 

 the chief directive receptors, such as the visual, chemo- 

 tactic, and auditory organs, in single pairs centralized 

 at the anterior end of the body; with the affectors, such 

 as muscles, appendages, and other organs, arranged in 

 graded linear series symmetrically paired, and appar- 

 ently with definite functional connections, point for 

 point, between these receptors and affectors. This 

 functional connection is made by means of paired con- 

 ductors (neurones, nerve fibres) extending longitudi- 

 nally, as well as right to left and left to right, which 



